case study about pollution

Suggested citation: Khan, Adeel, Uday Suryanarayanan, Tanushree Ganguly, and Karthik Ganesan. Improving Air Quality Management through Forecasts: A Case Study of Delhi’s Air Pollution of Winter 2021. New Delhi: Council on Energy, Environment and Water.

This study assesses Delhi’s air pollution scenario in the winter of 2021 and the actions to tackle it. Winter 2021 was unlike previous winters as the control measures mandated by the Commission of Air Quality Management (CAQM) in Delhi National Capital Region and adjoining areas were rolled out. These measures included the Graded Response Action Plan (GRAP) and additional emergency responses instituted on the basis of air quality and meteorological forecasts. Given that the forecasts play a major role in emergency response measures, the study assesses the reliability of different forecasts. Further, it gauges the impact of the emergency measures on Delhi’s air quality levels. It also discusses the primary driver of air pollution in winter 2021.

Key Findings

• While air quality forecasts picked up the pollution trends, they are not yet very accurate in predicting high pollution episodes ('very poor' and 'severe' air quality days)
• When the restrictions were in place like ban on entry of trucks, construction & demolition activities and others, air quality did not descend into the ‘severe +’ category. Moreover, air quality improved from ‘severe’ to ‘poor’ when all the restrictions were in place simultaneously, aided by better meteorology.
• However, when the restrictions were finally lifted, the air quality spiralled back into the ‘severe’ category resulting in the longest six days ‘severe’ air quality spell of the season.
• There has been no significant improvement in Delhi's winter air quality since 2019. In winter 2021, air quality was in the ‘very poor’ to ‘severe’ category on about 75 per cent of days.
• In the winter of 2021, transport(∼ 12 per cent), dust (∼ 7 per cent) and domestic biomass burning (∼ 6 per cent) were the largest local contributors.
• About 64 per cent of Delhi’s winter pollution load comes from outside of Delhi’s boundaries.

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Executive Summary

With every passing winter, the need to address Delhi’s air pollution grows more urgent. During the winter of 2021, the Supreme Court, the Delhi Government, and the Commission for Air Quality Management in the NCR and Adjoining Areas (CAQM), all sprang into action to arrest rising pollution levels in Delhi. The interventions ranged from shutting down power plants and restricting the entry of trucks into Delhi to school closures and using forecasts to pre-emptively roll out emergency measures. However, the impact of these interventions on Delhi’s air quality begs further investigation.

Through this study, we intend to examine what worked and what did not this season. As is the case every year, meteorological conditions played an important role in both aggravating and alleviating pollution levels. To assess the impact of meteorological conditions on pollution levels, we analysed pollution levels during the months of October to January vis-a-vis meteorological parameters. To understand the driving causes of pollution in the winter of 2021, we tracked the changes in relative contribution of various polluting sources as the season progressed.

While pre-emptive actions based on forecasts was a step in the right direction, an assessment of forecast performance is a prerequisite to integrating them in decision-making. We also assessed the performance of forecasts by comparing them with the measured onground concentrations. We also studied the timing and effectiveness of emergency directions issued in response to forecasts.

We sourced data on pollution levels from Central Pollution Control Board’s (CPCB) real-time air quality data portal and meteorological information from ECMWF Reanalysis v5 (ERA5). For information on modelled concentration and source contributions, we used data from publicly available air quality forecasts, including Delhi’s Air Quality Early Warning System (AQ-EWS) (3-day and 10-day), the Decision Support System for Air Quality Management in Delhi (DSS), and UrbanEmissions.Info (UE).

Figure ES1 In Delhi, 75% of Winter 2021 saw 'very poor' to 'severe' air quality

Source: Authors’ analysis, data from Central Pollution Control Board (CPCB). Note: Air quality index (AQI) for the day is calculated using the PM2.5 concentration at the same stations with a minimum of 75 per cent of the data being available.

A. 75 per cent of days were in ‘Very poor’ to ‘Severe’ air quality during winter 2021

The number of ‘Severe’ plus ‘Very poor’ air quality days during the winter has not decreased in the last three years (Figure ES1). During the winter of 2021 (15 October 2021 - 15 January 2022), about 75 per cent of the days, air quality were in the ‘Very poor’ to ‘Severe’ category. Interestingly, despite more farm fire incidents in Punjab, Haryana, and Uttar Pradesh in 2021 compared to 2020, Delhi’s PM2.5 concentration during the stubble burning phase (i.e., 15 October to 15 November) was lesser in 2021. This was primarily due to better meteorological conditions like higher wind speed and more number of rainy days during this period.

B. Regional influence predominant; Transport, dust, and domestic biomass burning are the largest local contributors to air pollution

We find that about 64 per cent of Delhi’s winter pollution load comes from outside Delhi’s boundaries (Figure ES2(a). Biomass burning of agricultural waste during the stubble burning phase and burning for heating and cooking needs during peak winter are estimated to be the major sources of air pollution from outside the city according to UE (Figure ES2(b). Locally, transport (12 per cent), dust (7 per cent), and domestic biomass burning (6 per cent) contribute the most to the PM2.5 pollution load of the city. While transport and dust are perennial sources of pollution in the city, the residential space heating component is a seasonal source. However, this seasonal contribution is so significant that as the use of biomass as a heat source in and around Delhi starts going up as winter progresses, the residential sector becomes the single-largest contributor by 15 December (Figure ES2(b)). This indicates the need to ramp up programmes to encourage households to shift to cleaner fuels for cooking and space heating.

Figure ES 2(a) Transport, dust, and domestic biomass burning are the largest local contributors to the PM2.5 pollution load in Delhi

Source: Authors’ analysis, source contribution data from DSS and UE. Note: Modelled estimates of relative source contributions retrieved from UE and DSS.

Figure ES 2(b) Both local and regional sources need to be targeted for reducing Delhi’s pollution

Source: Authors’ analysis, source contribution data from UE. Note: Source contribution data retrieved from UE district products which have larger geographical cover and lower resolution.

C. Forecasts picked up the pollution trend but could not predict high pollution episodes

The availability of multiple forecasts provides decisionmakers with a range of options to choose from. At the same time, this is an obstacle to effective onground action. To streamline the flow of relevant information from forecasters to decision-makers, it is important to analyse the forecasts and assess their reliability. We found that all the forecasts identified pollution trends accurately (Figure ES3) but their accuracy in predicting pollution episodes (‘Severe’ and ‘Very Poor’ air quality days) decreases with future time horizon.

D. Though forecasts were used to impose restrictions, the lifting of the curbs was ill-timed

In November–December 2021, apart from the Graded Response Action Plan (GRAP) coming into effect in DelhiNCR, the CAQM introduced several emergency response measures through a series of directions and orders. The Supreme Court also stepped in from time to time to direct the authorities to act on air pollution.

As a first, the CAQM used air quality and meteorological forecasts to time and tailor emergency response actions. The first set of restrictions was put in place on 16 November 2021, and all were lifted by 20 December 2021, save the one on industrial operations.

Figure ES3 All the forecasts can predict the trend accurately

Source: Authors’ analysis, data from Central Pollution Control Board (CPCB), AQ-EWS, and UE. Note: r represents correlation.

During this period, all the forecasts except AQ-EWS (3-day) underpredicted PM2.5 levels. Therefore, by looking at the difference between forecasted and measured concentrations, it is not possible to gauge the effectiveness of the restrictions conclusively. Hence, multiple models or different modelling experiments are needed to estimate the impact of the intervention.

It should be noted that during the restriction period, air quality did not descend into the ‘Severe +’ category. Further, when all the restrictions were in place along with better meteorology, air quality did improve from ‘Severe’ to ‘Poor’. The first prolonged ‘Severe’ air quality period in December was witnessed between 21 December and 26 December. While the forecasts sounded an alarm for high pollution levels during this period, all restrictions barring those on industrial activities were lifted. Subsequently, PM2.5 levels remained above 250 µgm -3 for six straight days resulting in the longest ‘Severe’ air quality spell of the season. (Figure ES4).

Figure ES4 The lifting of the restrictions was ill-timed with high pollution levels forecasted in the following days

Source: Authors’ analysis, data from Central Pollution Control Board (CPCB). Note: C&D stands for construction and demolition activities. Work from home (WFH) stands for the 50% cap on employee attendance in the office. Industrial restrictions stand for compulsory switching over to Piped Natural Gas (PNG) or other cleaner fuels within industries and non-compliant industries being allowed to operate restrictively.

The discussion above highlights that despite the emergency measures taken in winter 2021, the air quality conditions were far from satisfactory. Calibrating emergency responses to forecasted source contributions may result in a greater impact on air quality. Our study recommends the following to help the Government of National Capital Territory of Delhi ( GNCTD) and CAQM plan and execute emergency responses better:

• GRAP implementation must be based strictly on modelled source contributions obtained from forecasts and timed accordingly. This will eliminate the need for ad-hoc emergency directions to restrict various activities. For instance, restrictions on private vehicles can be brought in when the air quality is forecasted to be ‘Very poor’ as transport is a significant contributor.
• Surveys or assessments are required in the residential areas across NCR to explore the prevalence of biomass usage for heating and cooking purposes. Based on this, a targeted support mechanism is required to allow households and others to use clean fuels for cooking and heating. There is also a need to assess and promote alternatives for space heating.
• Air quality forecasts should be relayed to the public via social media platforms to encourage them to take preventive measures such as avoiding unnecessary travel and wearing masks when stepping out. This will help reduce individual exposure and activity levels in the city.
• Ground level data and insights need to be incorporated in forecasting models. Data from sources like social media posts (text and photos), camera feeds from public places, and pollution related grievance portals like SAMEER, Green Delhi, and SDMC 311 can provide near-real time information on pollution sources. Then aggregated representation of polluting activities based on recent days or weeks can be used as an input in models. Ultimately, a crowd-sourced emissions inventory for NCT/NCR will benefit modellers and policymakers alike while also making pollution curtailment efforts transparent.
• Combining the available air quality forecasts through an ensemble approach can help improve the accuracy of the forecasts and prompt better coordination within the modelling community.

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Environmental and Health Impacts of Air Pollution: A Review

Ioannis manisalidis.

1 Delphis S.A., Kifisia, Greece

2 Laboratory of Hygiene and Environmental Protection, Faculty of Medicine, Democritus University of Thrace, Alexandroupolis, Greece

Elisavet Stavropoulou

3 Centre Hospitalier Universitaire Vaudois (CHUV), Service de Médicine Interne, Lausanne, Switzerland

Agathangelos Stavropoulos

4 School of Social and Political Sciences, University of Glasgow, Glasgow, United Kingdom

Eugenia Bezirtzoglou

One of our era's greatest scourges is air pollution, on account not only of its impact on climate change but also its impact on public and individual health due to increasing morbidity and mortality. There are many pollutants that are major factors in disease in humans. Among them, Particulate Matter (PM), particles of variable but very small diameter, penetrate the respiratory system via inhalation, causing respiratory and cardiovascular diseases, reproductive and central nervous system dysfunctions, and cancer. Despite the fact that ozone in the stratosphere plays a protective role against ultraviolet irradiation, it is harmful when in high concentration at ground level, also affecting the respiratory and cardiovascular system. Furthermore, nitrogen oxide, sulfur dioxide, Volatile Organic Compounds (VOCs), dioxins, and polycyclic aromatic hydrocarbons (PAHs) are all considered air pollutants that are harmful to humans. Carbon monoxide can even provoke direct poisoning when breathed in at high levels. Heavy metals such as lead, when absorbed into the human body, can lead to direct poisoning or chronic intoxication, depending on exposure. Diseases occurring from the aforementioned substances include principally respiratory problems such as Chronic Obstructive Pulmonary Disease (COPD), asthma, bronchiolitis, and also lung cancer, cardiovascular events, central nervous system dysfunctions, and cutaneous diseases. Last but not least, climate change resulting from environmental pollution affects the geographical distribution of many infectious diseases, as do natural disasters. The only way to tackle this problem is through public awareness coupled with a multidisciplinary approach by scientific experts; national and international organizations must address the emergence of this threat and propose sustainable solutions.

Approach to the Problem

The interactions between humans and their physical surroundings have been extensively studied, as multiple human activities influence the environment. The environment is a coupling of the biotic (living organisms and microorganisms) and the abiotic (hydrosphere, lithosphere, and atmosphere).

Pollution is defined as the introduction into the environment of substances harmful to humans and other living organisms. Pollutants are harmful solids, liquids, or gases produced in higher than usual concentrations that reduce the quality of our environment.

Human activities have an adverse effect on the environment by polluting the water we drink, the air we breathe, and the soil in which plants grow. Although the industrial revolution was a great success in terms of technology, society, and the provision of multiple services, it also introduced the production of huge quantities of pollutants emitted into the air that are harmful to human health. Without any doubt, the global environmental pollution is considered an international public health issue with multiple facets. Social, economic, and legislative concerns and lifestyle habits are related to this major problem. Clearly, urbanization and industrialization are reaching unprecedented and upsetting proportions worldwide in our era. Anthropogenic air pollution is one of the biggest public health hazards worldwide, given that it accounts for about 9 million deaths per year ( 1 ).

Without a doubt, all of the aforementioned are closely associated with climate change, and in the event of danger, the consequences can be severe for mankind ( 2 ). Climate changes and the effects of global planetary warming seriously affect multiple ecosystems, causing problems such as food safety issues, ice and iceberg melting, animal extinction, and damage to plants ( 3 , 4 ).

Air pollution has various health effects. The health of susceptible and sensitive individuals can be impacted even on low air pollution days. Short-term exposure to air pollutants is closely related to COPD (Chronic Obstructive Pulmonary Disease), cough, shortness of breath, wheezing, asthma, respiratory disease, and high rates of hospitalization (a measurement of morbidity).

The long-term effects associated with air pollution are chronic asthma, pulmonary insufficiency, cardiovascular diseases, and cardiovascular mortality. According to a Swedish cohort study, diabetes seems to be induced after long-term air pollution exposure ( 5 ). Moreover, air pollution seems to have various malign health effects in early human life, such as respiratory, cardiovascular, mental, and perinatal disorders ( 3 ), leading to infant mortality or chronic disease in adult age ( 6 ).

National reports have mentioned the increased risk of morbidity and mortality ( 1 ). These studies were conducted in many places around the world and show a correlation between daily ranges of particulate matter (PM) concentration and daily mortality. Climate shifts and global planetary warming ( 3 ) could aggravate the situation. Besides, increased hospitalization (an index of morbidity) has been registered among the elderly and susceptible individuals for specific reasons. Fine and ultrafine particulate matter seems to be associated with more serious illnesses ( 6 ), as it can invade the deepest parts of the airways and more easily reach the bloodstream.

Air pollution mainly affects those living in large urban areas, where road emissions contribute the most to the degradation of air quality. There is also a danger of industrial accidents, where the spread of a toxic fog can be fatal to the populations of the surrounding areas. The dispersion of pollutants is determined by many parameters, most notably atmospheric stability and wind ( 6 ).

In developing countries ( 7 ), the problem is more serious due to overpopulation and uncontrolled urbanization along with the development of industrialization. This leads to poor air quality, especially in countries with social disparities and a lack of information on sustainable management of the environment. The use of fuels such as wood fuel or solid fuel for domestic needs due to low incomes exposes people to bad-quality, polluted air at home. It is of note that three billion people around the world are using the above sources of energy for their daily heating and cooking needs ( 8 ). In developing countries, the women of the household seem to carry the highest risk for disease development due to their longer duration exposure to the indoor air pollution ( 8 , 9 ). Due to its fast industrial development and overpopulation, China is one of the Asian countries confronting serious air pollution problems ( 10 , 11 ). The lung cancer mortality observed in China is associated with fine particles ( 12 ). As stated already, long-term exposure is associated with deleterious effects on the cardiovascular system ( 3 , 5 ). However, it is interesting to note that cardiovascular diseases have mostly been observed in developed and high-income countries rather than in the developing low-income countries exposed highly to air pollution ( 13 ). Extreme air pollution is recorded in India, where the air quality reaches hazardous levels. New Delhi is one of the more polluted cities in India. Flights in and out of New Delhi International Airport are often canceled due to the reduced visibility associated with air pollution. Pollution is occurring both in urban and rural areas in India due to the fast industrialization, urbanization, and rise in use of motorcycle transportation. Nevertheless, biomass combustion associated with heating and cooking needs and practices is a major source of household air pollution in India and in Nepal ( 14 , 15 ). There is spatial heterogeneity in India, as areas with diverse climatological conditions and population and education levels generate different indoor air qualities, with higher PM 2.5 observed in North Indian states (557–601 μg/m 3 ) compared to the Southern States (183–214 μg/m 3 ) ( 16 , 17 ). The cold climate of the North Indian areas may be the main reason for this, as longer periods at home and more heating are necessary compared to in the tropical climate of Southern India. Household air pollution in India is associated with major health effects, especially in women and young children, who stay indoors for longer periods. Chronic obstructive respiratory disease (CORD) and lung cancer are mostly observed in women, while acute lower respiratory disease is seen in young children under 5 years of age ( 18 ).

Accumulation of air pollution, especially sulfur dioxide and smoke, reaching 1,500 mg/m3, resulted in an increase in the number of deaths (4,000 deaths) in December 1952 in London and in 1963 in New York City (400 deaths) ( 19 ). An association of pollution with mortality was reported on the basis of monitoring of outdoor pollution in six US metropolitan cities ( 20 ). In every case, it seems that mortality was closely related to the levels of fine, inhalable, and sulfate particles more than with the levels of total particulate pollution, aerosol acidity, sulfur dioxide, or nitrogen dioxide ( 20 ).

Furthermore, extremely high levels of pollution are reported in Mexico City and Rio de Janeiro, followed by Milan, Ankara, Melbourne, Tokyo, and Moscow ( 19 ).

Based on the magnitude of the public health impact, it is certain that different kinds of interventions should be taken into account. Success and effectiveness in controlling air pollution, specifically at the local level, have been reported. Adequate technological means are applied considering the source and the nature of the emission as well as its impact on health and the environment. The importance of point sources and non-point sources of air pollution control is reported by Schwela and Köth-Jahr ( 21 ). Without a doubt, a detailed emission inventory must record all sources in a given area. Beyond considering the above sources and their nature, topography and meteorology should also be considered, as stated previously. Assessment of the control policies and methods is often extrapolated from the local to the regional and then to the global scale. Air pollution may be dispersed and transported from one region to another area located far away. Air pollution management means the reduction to acceptable levels or possible elimination of air pollutants whose presence in the air affects our health or the environmental ecosystem. Private and governmental entities and authorities implement actions to ensure the air quality ( 22 ). Air quality standards and guidelines were adopted for the different pollutants by the WHO and EPA as a tool for the management of air quality ( 1 , 23 ). These standards have to be compared to the emissions inventory standards by causal analysis and dispersion modeling in order to reveal the problematic areas ( 24 ). Inventories are generally based on a combination of direct measurements and emissions modeling ( 24 ).

As an example, we state here the control measures at the source through the use of catalytic converters in cars. These are devices that turn the pollutants and toxic gases produced from combustion engines into less-toxic pollutants by catalysis through redox reactions ( 25 ). In Greece, the use of private cars was restricted by tracking their license plates in order to reduce traffic congestion during rush hour ( 25 ).

Concerning industrial emissions, collectors and closed systems can keep the air pollution to the minimal standards imposed by legislation ( 26 ).

Current strategies to improve air quality require an estimation of the economic value of the benefits gained from proposed programs. These proposed programs by public authorities, and directives are issued with guidelines to be respected.

In Europe, air quality limit values AQLVs (Air Quality Limit Values) are issued for setting off planning claims ( 27 ). In the USA, the NAAQS (National Ambient Air Quality Standards) establish the national air quality limit values ( 27 ). While both standards and directives are based on different mechanisms, significant success has been achieved in the reduction of overall emissions and associated health and environmental effects ( 27 ). The European Directive identifies geographical areas of risk exposure as monitoring/assessment zones to record the emission sources and levels of air pollution ( 27 ), whereas the USA establishes global geographical air quality criteria according to the severity of their air quality problem and records all sources of the pollutants and their precursors ( 27 ).

In this vein, funds have been financing, directly or indirectly, projects related to air quality along with the technical infrastructure to maintain good air quality. These plans focus on an inventory of databases from air quality environmental planning awareness campaigns. Moreover, pollution measures of air emissions may be taken for vehicles, machines, and industries in urban areas.

Technological innovation can only be successful if it is able to meet the needs of society. In this sense, technology must reflect the decision-making practices and procedures of those involved in risk assessment and evaluation and act as a facilitator in providing information and assessments to enable decision makers to make the best decisions possible. Summarizing the aforementioned in order to design an effective air quality control strategy, several aspects must be considered: environmental factors and ambient air quality conditions, engineering factors and air pollutant characteristics, and finally, economic operating costs for technological improvement and administrative and legal costs. Considering the economic factor, competitiveness through neoliberal concepts is offering a solution to environmental problems ( 22 ).

The development of environmental governance, along with technological progress, has initiated the deployment of a dialogue. Environmental politics has created objections and points of opposition between different political parties, scientists, media, and governmental and non-governmental organizations ( 22 ). Radical environmental activism actions and movements have been created ( 22 ). The rise of the new information and communication technologies (ICTs) are many times examined as to whether and in which way they have influenced means of communication and social movements such as activism ( 28 ). Since the 1990s, the term “digital activism” has been used increasingly and in many different disciplines ( 29 ). Nowadays, multiple digital technologies can be used to produce a digital activism outcome on environmental issues. More specifically, devices with online capabilities such as computers or mobile phones are being used as a way to pursue change in political and social affairs ( 30 ).

In the present paper, we focus on the sources of environmental pollution in relation to public health and propose some solutions and interventions that may be of interest to environmental legislators and decision makers.

Sources of Exposure

It is known that the majority of environmental pollutants are emitted through large-scale human activities such as the use of industrial machinery, power-producing stations, combustion engines, and cars. Because these activities are performed at such a large scale, they are by far the major contributors to air pollution, with cars estimated to be responsible for approximately 80% of today's pollution ( 31 ). Some other human activities are also influencing our environment to a lesser extent, such as field cultivation techniques, gas stations, fuel tanks heaters, and cleaning procedures ( 32 ), as well as several natural sources, such as volcanic and soil eruptions and forest fires.

The classification of air pollutants is based mainly on the sources producing pollution. Therefore, it is worth mentioning the four main sources, following the classification system: Major sources, Area sources, Mobile sources, and Natural sources.

Major sources include the emission of pollutants from power stations, refineries, and petrochemicals, the chemical and fertilizer industries, metallurgical and other industrial plants, and, finally, municipal incineration.

Indoor area sources include domestic cleaning activities, dry cleaners, printing shops, and petrol stations.

Mobile sources include automobiles, cars, railways, airways, and other types of vehicles.

Finally, natural sources include, as stated previously, physical disasters ( 33 ) such as forest fire, volcanic erosion, dust storms, and agricultural burning.

However, many classification systems have been proposed. Another type of classification is a grouping according to the recipient of the pollution, as follows:

Air pollution is determined as the presence of pollutants in the air in large quantities for long periods. Air pollutants are dispersed particles, hydrocarbons, CO, CO 2 , NO, NO 2 , SO 3 , etc.

Water pollution is organic and inorganic charge and biological charge ( 10 ) at high levels that affect the water quality ( 34 , 35 ).

Soil pollution occurs through the release of chemicals or the disposal of wastes, such as heavy metals, hydrocarbons, and pesticides.

Air pollution can influence the quality of soil and water bodies by polluting precipitation, falling into water and soil environments ( 34 , 36 ). Notably, the chemistry of the soil can be amended due to acid precipitation by affecting plants, cultures, and water quality ( 37 ). Moreover, movement of heavy metals is favored by soil acidity, and metals are so then moving into the watery environment. It is known that heavy metals such as aluminum are noxious to wildlife and fishes. Soil quality seems to be of importance, as soils with low calcium carbonate levels are at increased jeopardy from acid rain. Over and above rain, snow and particulate matter drip into watery ' bodies ( 36 , 38 ).

Lastly, pollution is classified following type of origin:

Radioactive and nuclear pollution , releasing radioactive and nuclear pollutants into water, air, and soil during nuclear explosions and accidents, from nuclear weapons, and through handling or disposal of radioactive sewage.

Radioactive materials can contaminate surface water bodies and, being noxious to the environment, plants, animals, and humans. It is known that several radioactive substances such as radium and uranium concentrate in the bones and can cause cancers ( 38 , 39 ).

Noise pollution is produced by machines, vehicles, traffic noises, and musical installations that are harmful to our hearing.

The World Health Organization introduced the term DALYs. The DALYs for a disease or health condition is defined as the sum of the Years of Life Lost (YLL) due to premature mortality in the population and the Years Lost due to Disability (YLD) for people living with the health condition or its consequences ( 39 ). In Europe, air pollution is the main cause of disability-adjusted life years lost (DALYs), followed by noise pollution. The potential relationships of noise and air pollution with health have been studied ( 40 ). The study found that DALYs related to noise were more important than those related to air pollution, as the effects of environmental noise on cardiovascular disease were independent of air pollution ( 40 ). Environmental noise should be counted as an independent public health risk ( 40 ).

Environmental pollution occurs when changes in the physical, chemical, or biological constituents of the environment (air masses, temperature, climate, etc.) are produced.

Pollutants harm our environment either by increasing levels above normal or by introducing harmful toxic substances. Primary pollutants are directly produced from the above sources, and secondary pollutants are emitted as by-products of the primary ones. Pollutants can be biodegradable or non-biodegradable and of natural origin or anthropogenic, as stated previously. Moreover, their origin can be a unique source (point-source) or dispersed sources.

Pollutants have differences in physical and chemical properties, explaining the discrepancy in their capacity for producing toxic effects. As an example, we state here that aerosol compounds ( 41 – 43 ) have a greater toxicity than gaseous compounds due to their tiny size (solid or liquid) in the atmosphere; they have a greater penetration capacity. Gaseous compounds are eliminated more easily by our respiratory system ( 41 ). These particles are able to damage lungs and can even enter the bloodstream ( 41 ), leading to the premature deaths of millions of people yearly. Moreover, the aerosol acidity ([H+]) seems to considerably enhance the production of secondary organic aerosols (SOA), but this last aspect is not supported by other scientific teams ( 38 ).

Climate and Pollution

Air pollution and climate change are closely related. Climate is the other side of the same coin that reduces the quality of our Earth ( 44 ). Pollutants such as black carbon, methane, tropospheric ozone, and aerosols affect the amount of incoming sunlight. As a result, the temperature of the Earth is increasing, resulting in the melting of ice, icebergs, and glaciers.

In this vein, climatic changes will affect the incidence and prevalence of both residual and imported infections in Europe. Climate and weather affect the duration, timing, and intensity of outbreaks strongly and change the map of infectious diseases in the globe ( 45 ). Mosquito-transmitted parasitic or viral diseases are extremely climate-sensitive, as warming firstly shortens the pathogen incubation period and secondly shifts the geographic map of the vector. Similarly, water-warming following climate changes leads to a high incidence of waterborne infections. Recently, in Europe, eradicated diseases seem to be emerging due to the migration of population, for example, cholera, poliomyelitis, tick-borne encephalitis, and malaria ( 46 ).

The spread of epidemics is associated with natural climate disasters and storms, which seem to occur more frequently nowadays ( 47 ). Malnutrition and disequilibration of the immune system are also associated with the emerging infections affecting public health ( 48 ).

The Chikungunya virus “took the airplane” from the Indian Ocean to Europe, as outbreaks of the disease were registered in Italy ( 49 ) as well as autochthonous cases in France ( 50 ).

An increase in cryptosporidiosis in the United Kingdom and in the Czech Republic seems to have occurred following flooding ( 36 , 51 ).

As stated previously, aerosols compounds are tiny in size and considerably affect the climate. They are able to dissipate sunlight (the albedo phenomenon) by dispersing a quarter of the sun's rays back to space and have cooled the global temperature over the last 30 years ( 52 ).

Air Pollutants

The World Health Organization (WHO) reports on six major air pollutants, namely particle pollution, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead. Air pollution can have a disastrous effect on all components of the environment, including groundwater, soil, and air. Additionally, it poses a serious threat to living organisms. In this vein, our interest is mainly to focus on these pollutants, as they are related to more extensive and severe problems in human health and environmental impact. Acid rain, global warming, the greenhouse effect, and climate changes have an important ecological impact on air pollution ( 53 ).

Particulate Matter (PM) and Health

Studies have shown a relationship between particulate matter (PM) and adverse health effects, focusing on either short-term (acute) or long-term (chronic) PM exposure.

Particulate matter (PM) is usually formed in the atmosphere as a result of chemical reactions between the different pollutants. The penetration of particles is closely dependent on their size ( 53 ). Particulate Matter (PM) was defined as a term for particles by the United States Environmental Protection Agency ( 54 ). Particulate matter (PM) pollution includes particles with diameters of 10 micrometers (μm) or smaller, called PM 10 , and extremely fine particles with diameters that are generally 2.5 micrometers (μm) and smaller.

Particulate matter contains tiny liquid or solid droplets that can be inhaled and cause serious health effects ( 55 ). Particles <10 μm in diameter (PM 10 ) after inhalation can invade the lungs and even reach the bloodstream. Fine particles, PM 2.5 , pose a greater risk to health ( 6 , 56 ) ( Table 1 ).

Penetrability according to particle size.

Multiple epidemiological studies have been performed on the health effects of PM. A positive relation was shown between both short-term and long-term exposures of PM 2.5 and acute nasopharyngitis ( 56 ). In addition, long-term exposure to PM for years was found to be related to cardiovascular diseases and infant mortality.

Those studies depend on PM 2.5 monitors and are restricted in terms of study area or city area due to a lack of spatially resolved daily PM 2.5 concentration data and, in this way, are not representative of the entire population. Following a recent epidemiological study by the Department of Environmental Health at Harvard School of Public Health (Boston, MA) ( 57 ), it was reported that, as PM 2.5 concentrations vary spatially, an exposure error (Berkson error) seems to be produced, and the relative magnitudes of the short- and long-term effects are not yet completely elucidated. The team developed a PM 2.5 exposure model based on remote sensing data for assessing short- and long-term human exposures ( 57 ). This model permits spatial resolution in short-term effects plus the assessment of long-term effects in the whole population.

Moreover, respiratory diseases and affection of the immune system are registered as long-term chronic effects ( 58 ). It is worth noting that people with asthma, pneumonia, diabetes, and respiratory and cardiovascular diseases are especially susceptible and vulnerable to the effects of PM. PM 2.5 , followed by PM 10 , are strongly associated with diverse respiratory system diseases ( 59 ), as their size permits them to pierce interior spaces ( 60 ). The particles produce toxic effects according to their chemical and physical properties. The components of PM 10 and PM 2.5 can be organic (polycyclic aromatic hydrocarbons, dioxins, benzene, 1-3 butadiene) or inorganic (carbon, chlorides, nitrates, sulfates, metals) in nature ( 55 ).

Particulate Matter (PM) is divided into four main categories according to type and size ( 61 ) ( Table 2 ).

Types and sizes of particulate Matter (PM).

Gas contaminants include PM in aerial masses.

Particulate contaminants include contaminants such as smog, soot, tobacco smoke, oil smoke, fly ash, and cement dust.

Biological Contaminants are microorganisms (bacteria, viruses, fungi, mold, and bacterial spores), cat allergens, house dust and allergens, and pollen.

Types of Dust include suspended atmospheric dust, settling dust, and heavy dust.

Finally, another fact is that the half-lives of PM 10 and PM 2.5 particles in the atmosphere is extended due to their tiny dimensions; this permits their long-lasting suspension in the atmosphere and even their transfer and spread to distant destinations where people and the environment may be exposed to the same magnitude of pollution ( 53 ). They are able to change the nutrient balance in watery ecosystems, damage forests and crops, and acidify water bodies.

As stated, PM 2.5 , due to their tiny size, are causing more serious health effects. These aforementioned fine particles are the main cause of the “haze” formation in different metropolitan areas ( 12 , 13 , 61 ).

Ozone Impact in the Atmosphere

Ozone (O 3 ) is a gas formed from oxygen under high voltage electric discharge ( 62 ). It is a strong oxidant, 52% stronger than chlorine. It arises in the stratosphere, but it could also arise following chain reactions of photochemical smog in the troposphere ( 63 ).

Ozone can travel to distant areas from its initial source, moving with air masses ( 64 ). It is surprising that ozone levels over cities are low in contrast to the increased amounts occuring in urban areas, which could become harmful for cultures, forests, and vegetation ( 65 ) as it is reducing carbon assimilation ( 66 ). Ozone reduces growth and yield ( 47 , 48 ) and affects the plant microflora due to its antimicrobial capacity ( 67 , 68 ). In this regard, ozone acts upon other natural ecosystems, with microflora ( 69 , 70 ) and animal species changing their species composition ( 71 ). Ozone increases DNA damage in epidermal keratinocytes and leads to impaired cellular function ( 72 ).

Ground-level ozone (GLO) is generated through a chemical reaction between oxides of nitrogen and VOCs emitted from natural sources and/or following anthropogenic activities.

Ozone uptake usually occurs by inhalation. Ozone affects the upper layers of the skin and the tear ducts ( 73 ). A study of short-term exposure of mice to high levels of ozone showed malondialdehyde formation in the upper skin (epidermis) but also depletion in vitamins C and E. It is likely that ozone levels are not interfering with the skin barrier function and integrity to predispose to skin disease ( 74 ).

Due to the low water-solubility of ozone, inhaled ozone has the capacity to penetrate deeply into the lungs ( 75 ).

Toxic effects induced by ozone are registered in urban areas all over the world, causing biochemical, morphologic, functional, and immunological disorders ( 76 ).

The European project (APHEA2) focuses on the acute effects of ambient ozone concentrations on mortality ( 77 ). Daily ozone concentrations compared to the daily number of deaths were reported from different European cities for a 3-year period. During the warm period of the year, an observed increase in ozone concentration was associated with an increase in the daily number of deaths (0.33%), in the number of respiratory deaths (1.13%), and in the number of cardiovascular deaths (0.45%). No effect was observed during wintertime.

Carbon Monoxide (CO)

Carbon monoxide is produced by fossil fuel when combustion is incomplete. The symptoms of poisoning due to inhaling carbon monoxide include headache, dizziness, weakness, nausea, vomiting, and, finally, loss of consciousness.

The affinity of carbon monoxide to hemoglobin is much greater than that of oxygen. In this vein, serious poisoning may occur in people exposed to high levels of carbon monoxide for a long period of time. Due to the loss of oxygen as a result of the competitive binding of carbon monoxide, hypoxia, ischemia, and cardiovascular disease are observed.

Carbon monoxide affects the greenhouses gases that are tightly connected to global warming and climate. This should lead to an increase in soil and water temperatures, and extreme weather conditions or storms may occur ( 68 ).

However, in laboratory and field experiments, it has been seen to produce increased plant growth ( 78 ).

Nitrogen Oxide (NO 2 )

Nitrogen oxide is a traffic-related pollutant, as it is emitted from automobile motor engines ( 79 , 80 ). It is an irritant of the respiratory system as it penetrates deep in the lung, inducing respiratory diseases, coughing, wheezing, dyspnea, bronchospasm, and even pulmonary edema when inhaled at high levels. It seems that concentrations over 0.2 ppm produce these adverse effects in humans, while concentrations higher than 2.0 ppm affect T-lymphocytes, particularly the CD8+ cells and NK cells that produce our immune response ( 81 ).It is reported that long-term exposure to high levels of nitrogen dioxide can be responsible for chronic lung disease. Long-term exposure to NO 2 can impair the sense of smell ( 81 ).

However, systems other than respiratory ones can be involved, as symptoms such as eye, throat, and nose irritation have been registered ( 81 ).

High levels of nitrogen dioxide are deleterious to crops and vegetation, as they have been observed to reduce crop yield and plant growth efficiency. Moreover, NO 2 can reduce visibility and discolor fabrics ( 81 ).

Sulfur Dioxide (SO 2 )

Sulfur dioxide is a harmful gas that is emitted mainly from fossil fuel consumption or industrial activities. The annual standard for SO 2 is 0.03 ppm ( 82 ). It affects human, animal, and plant life. Susceptible people as those with lung disease, old people, and children, who present a higher risk of damage. The major health problems associated with sulfur dioxide emissions in industrialized areas are respiratory irritation, bronchitis, mucus production, and bronchospasm, as it is a sensory irritant and penetrates deep into the lung converted into bisulfite and interacting with sensory receptors, causing bronchoconstriction. Moreover, skin redness, damage to the eyes (lacrimation and corneal opacity) and mucous membranes, and worsening of pre-existing cardiovascular disease have been observed ( 81 ).

Environmental adverse effects, such as acidification of soil and acid rain, seem to be associated with sulfur dioxide emissions ( 83 ).

Lead is a heavy metal used in different industrial plants and emitted from some petrol motor engines, batteries, radiators, waste incinerators, and waste waters ( 84 ).

Moreover, major sources of lead pollution in the air are metals, ore, and piston-engine aircraft. Lead poisoning is a threat to public health due to its deleterious effects upon humans, animals, and the environment, especially in the developing countries.

Exposure to lead can occur through inhalation, ingestion, and dermal absorption. Trans- placental transport of lead was also reported, as lead passes through the placenta unencumbered ( 85 ). The younger the fetus is, the more harmful the toxic effects. Lead toxicity affects the fetal nervous system; edema or swelling of the brain is observed ( 86 ). Lead, when inhaled, accumulates in the blood, soft tissue, liver, lung, bones, and cardiovascular, nervous, and reproductive systems. Moreover, loss of concentration and memory, as well as muscle and joint pain, were observed in adults ( 85 , 86 ).

Children and newborns ( 87 ) are extremely susceptible even to minimal doses of lead, as it is a neurotoxicant and causes learning disabilities, impairment of memory, hyperactivity, and even mental retardation.

Elevated amounts of lead in the environment are harmful to plants and crop growth. Neurological effects are observed in vertebrates and animals in association with high lead levels ( 88 ).

Polycyclic Aromatic Hydrocarbons(PAHs)

The distribution of PAHs is ubiquitous in the environment, as the atmosphere is the most important means of their dispersal. They are found in coal and in tar sediments. Moreover, they are generated through incomplete combustion of organic matter as in the cases of forest fires, incineration, and engines ( 89 ). PAH compounds, such as benzopyrene, acenaphthylene, anthracene, and fluoranthene are recognized as toxic, mutagenic, and carcinogenic substances. They are an important risk factor for lung cancer ( 89 ).

Volatile Organic Compounds(VOCs)

Volatile organic compounds (VOCs), such as toluene, benzene, ethylbenzene, and xylene ( 90 ), have been found to be associated with cancer in humans ( 91 ). The use of new products and materials has actually resulted in increased concentrations of VOCs. VOCs pollute indoor air ( 90 ) and may have adverse effects on human health ( 91 ). Short-term and long-term adverse effects on human health are observed. VOCs are responsible for indoor air smells. Short-term exposure is found to cause irritation of eyes, nose, throat, and mucosal membranes, while those of long duration exposure include toxic reactions ( 92 ). Predictable assessment of the toxic effects of complex VOC mixtures is difficult to estimate, as these pollutants can have synergic, antagonistic, or indifferent effects ( 91 , 93 ).

Dioxins originate from industrial processes but also come from natural processes, such as forest fires and volcanic eruptions. They accumulate in foods such as meat and dairy products, fish and shellfish, and especially in the fatty tissue of animals ( 94 ).

Short-period exhibition to high dioxin concentrations may result in dark spots and lesions on the skin ( 94 ). Long-term exposure to dioxins can cause developmental problems, impairment of the immune, endocrine and nervous systems, reproductive infertility, and cancer ( 94 ).

Without any doubt, fossil fuel consumption is responsible for a sizeable part of air contamination. This contamination may be anthropogenic, as in agricultural and industrial processes or transportation, while contamination from natural sources is also possible. Interestingly, it is of note that the air quality standards established through the European Air Quality Directive are somewhat looser than the WHO guidelines, which are stricter ( 95 ).

Effect of Air Pollution on Health

The most common air pollutants are ground-level ozone and Particulates Matter (PM). Air pollution is distinguished into two main types:

Outdoor pollution is the ambient air pollution.

Indoor pollution is the pollution generated by household combustion of fuels.

People exposed to high concentrations of air pollutants experience disease symptoms and states of greater and lesser seriousness. These effects are grouped into short- and long-term effects affecting health.

Susceptible populations that need to be aware of health protection measures include old people, children, and people with diabetes and predisposing heart or lung disease, especially asthma.

As extensively stated previously, according to a recent epidemiological study from Harvard School of Public Health, the relative magnitudes of the short- and long-term effects have not been completely clarified ( 57 ) due to the different epidemiological methodologies and to the exposure errors. New models are proposed for assessing short- and long-term human exposure data more successfully ( 57 ). Thus, in the present section, we report the more common short- and long-term health effects but also general concerns for both types of effects, as these effects are often dependent on environmental conditions, dose, and individual susceptibility.

Short-term effects are temporary and range from simple discomfort, such as irritation of the eyes, nose, skin, throat, wheezing, coughing and chest tightness, and breathing difficulties, to more serious states, such as asthma, pneumonia, bronchitis, and lung and heart problems. Short-term exposure to air pollution can also cause headaches, nausea, and dizziness.

These problems can be aggravated by extended long-term exposure to the pollutants, which is harmful to the neurological, reproductive, and respiratory systems and causes cancer and even, rarely, deaths.

The long-term effects are chronic, lasting for years or the whole life and can even lead to death. Furthermore, the toxicity of several air pollutants may also induce a variety of cancers in the long term ( 96 ).

As stated already, respiratory disorders are closely associated with the inhalation of air pollutants. These pollutants will invade through the airways and will accumulate at the cells. Damage to target cells should be related to the pollutant component involved and its source and dose. Health effects are also closely dependent on country, area, season, and time. An extended exposure duration to the pollutant should incline to long-term health effects in relation also to the above factors.

Particulate Matter (PMs), dust, benzene, and O 3 cause serious damage to the respiratory system ( 97 ). Moreover, there is a supplementary risk in case of existing respiratory disease such as asthma ( 98 ). Long-term effects are more frequent in people with a predisposing disease state. When the trachea is contaminated by pollutants, voice alterations may be remarked after acute exposure. Chronic obstructive pulmonary disease (COPD) may be induced following air pollution, increasing morbidity and mortality ( 99 ). Long-term effects from traffic, industrial air pollution, and combustion of fuels are the major factors for COPD risk ( 99 ).

Multiple cardiovascular effects have been observed after exposure to air pollutants ( 100 ). Changes occurred in blood cells after long-term exposure may affect cardiac functionality. Coronary arteriosclerosis was reported following long-term exposure to traffic emissions ( 101 ), while short-term exposure is related to hypertension, stroke, myocardial infracts, and heart insufficiency. Ventricle hypertrophy is reported to occur in humans after long-time exposure to nitrogen oxide (NO 2 ) ( 102 , 103 ).

Neurological effects have been observed in adults and children after extended-term exposure to air pollutants.

Psychological complications, autism, retinopathy, fetal growth, and low birth weight seem to be related to long-term air pollution ( 83 ). The etiologic agent of the neurodegenerative diseases (Alzheimer's and Parkinson's) is not yet known, although it is believed that extended exposure to air pollution seems to be a factor. Specifically, pesticides and metals are cited as etiological factors, together with diet. The mechanisms in the development of neurodegenerative disease include oxidative stress, protein aggregation, inflammation, and mitochondrial impairment in neurons ( 104 ) ( Figure 1 ).

Impact of air pollutants on the brain.

Brain inflammation was observed in dogs living in a highly polluted area in Mexico for a long period ( 105 ). In human adults, markers of systemic inflammation (IL-6 and fibrinogen) were found to be increased as an immediate response to PNC on the IL-6 level, possibly leading to the production of acute-phase proteins ( 106 ). The progression of atherosclerosis and oxidative stress seem to be the mechanisms involved in the neurological disturbances caused by long-term air pollution. Inflammation comes secondary to the oxidative stress and seems to be involved in the impairment of developmental maturation, affecting multiple organs ( 105 , 107 ). Similarly, other factors seem to be involved in the developmental maturation, which define the vulnerability to long-term air pollution. These include birthweight, maternal smoking, genetic background and socioeconomic environment, as well as education level.

However, diet, starting from breast-feeding, is another determinant factor. Diet is the main source of antioxidants, which play a key role in our protection against air pollutants ( 108 ). Antioxidants are free radical scavengers and limit the interaction of free radicals in the brain ( 108 ). Similarly, genetic background may result in a differential susceptibility toward the oxidative stress pathway ( 60 ). For example, antioxidant supplementation with vitamins C and E appears to modulate the effect of ozone in asthmatic children homozygous for the GSTM1 null allele ( 61 ). Inflammatory cytokines released in the periphery (e.g., respiratory epithelia) upregulate the innate immune Toll-like receptor 2. Such activation and the subsequent events leading to neurodegeneration have recently been observed in lung lavage in mice exposed to ambient Los Angeles (CA, USA) particulate matter ( 61 ). In children, neurodevelopmental morbidities were observed after lead exposure. These children developed aggressive and delinquent behavior, reduced intelligence, learning difficulties, and hyperactivity ( 109 ). No level of lead exposure seems to be “safe,” and the scientific community has asked the Centers for Disease Control and Prevention (CDC) to reduce the current screening guideline of 10 μg/dl ( 109 ).

It is important to state that impact on the immune system, causing dysfunction and neuroinflammation ( 104 ), is related to poor air quality. Yet, increases in serum levels of immunoglobulins (IgA, IgM) and the complement component C3 are observed ( 106 ). Another issue is that antigen presentation is affected by air pollutants, as there is an upregulation of costimulatory molecules such as CD80 and CD86 on macrophages ( 110 ).

As is known, skin is our shield against ultraviolet radiation (UVR) and other pollutants, as it is the most exterior layer of our body. Traffic-related pollutants, such as PAHs, VOCs, oxides, and PM, may cause pigmented spots on our skin ( 111 ). On the one hand, as already stated, when pollutants penetrate through the skin or are inhaled, damage to the organs is observed, as some of these pollutants are mutagenic and carcinogenic, and, specifically, they affect the liver and lung. On the other hand, air pollutants (and those in the troposphere) reduce the adverse effects of ultraviolet radiation UVR in polluted urban areas ( 111 ). Air pollutants absorbed by the human skin may contribute to skin aging, psoriasis, acne, urticaria, eczema, and atopic dermatitis ( 111 ), usually caused by exposure to oxides and photochemical smoke ( 111 ). Exposure to PM and cigarette smoking act as skin-aging agents, causing spots, dyschromia, and wrinkles. Lastly, pollutants have been associated with skin cancer ( 111 ).

Higher morbidity is reported to fetuses and children when exposed to the above dangers. Impairment in fetal growth, low birth weight, and autism have been reported ( 112 ).

Another exterior organ that may be affected is the eye. Contamination usually comes from suspended pollutants and may result in asymptomatic eye outcomes, irritation ( 112 ), retinopathy, or dry eye syndrome ( 113 , 114 ).

Environmental Impact of Air Pollution

Air pollution is harming not only human health but also the environment ( 115 ) in which we live. The most important environmental effects are as follows.

Acid rain is wet (rain, fog, snow) or dry (particulates and gas) precipitation containing toxic amounts of nitric and sulfuric acids. They are able to acidify the water and soil environments, damage trees and plantations, and even damage buildings and outdoor sculptures, constructions, and statues.

Haze is produced when fine particles are dispersed in the air and reduce the transparency of the atmosphere. It is caused by gas emissions in the air coming from industrial facilities, power plants, automobiles, and trucks.

Ozone , as discussed previously, occurs both at ground level and in the upper level (stratosphere) of the Earth's atmosphere. Stratospheric ozone is protecting us from the Sun's harmful ultraviolet (UV) rays. In contrast, ground-level ozone is harmful to human health and is a pollutant. Unfortunately, stratospheric ozone is gradually damaged by ozone-depleting substances (i.e., chemicals, pesticides, and aerosols). If this protecting stratospheric ozone layer is thinned, then UV radiation can reach our Earth, with harmful effects for human life (skin cancer) ( 116 ) and crops ( 117 ). In plants, ozone penetrates through the stomata, inducing them to close, which blocks CO 2 transfer and induces a reduction in photosynthesis ( 118 ).

Global climate change is an important issue that concerns mankind. As is known, the “greenhouse effect” keeps the Earth's temperature stable. Unhappily, anthropogenic activities have destroyed this protecting temperature effect by producing large amounts of greenhouse gases, and global warming is mounting, with harmful effects on human health, animals, forests, wildlife, agriculture, and the water environment. A report states that global warming is adding to the health risks of poor people ( 119 ).

People living in poorly constructed buildings in warm-climate countries are at high risk for heat-related health problems as temperatures mount ( 119 ).

Wildlife is burdened by toxic pollutants coming from the air, soil, or the water ecosystem and, in this way, animals can develop health problems when exposed to high levels of pollutants. Reproductive failure and birth effects have been reported.

Eutrophication is occurring when elevated concentrations of nutrients (especially nitrogen) stimulate the blooming of aquatic algae, which can cause a disequilibration in the diversity of fish and their deaths.

Without a doubt, there is a critical concentration of pollution that an ecosystem can tolerate without being destroyed, which is associated with the ecosystem's capacity to neutralize acidity. The Canada Acid Rain Program established this load at 20 kg/ha/yr ( 120 ).

Hence, air pollution has deleterious effects on both soil and water ( 121 ). Concerning PM as an air pollutant, its impact on crop yield and food productivity has been reported. Its impact on watery bodies is associated with the survival of living organisms and fishes and their productivity potential ( 121 ).

An impairment in photosynthetic rhythm and metabolism is observed in plants exposed to the effects of ozone ( 121 ).

Sulfur and nitrogen oxides are involved in the formation of acid rain and are harmful to plants and marine organisms.

Last but not least, as mentioned above, the toxicity associated with lead and other metals is the main threat to our ecosystems (air, water, and soil) and living creatures ( 121 ).

In 2018, during the first WHO Global Conference on Air Pollution and Health, the WHO's General Director, Dr. Tedros Adhanom Ghebreyesus, called air pollution a “silent public health emergency” and “the new tobacco” ( 122 ).

Undoubtedly, children are particularly vulnerable to air pollution, especially during their development. Air pollution has adverse effects on our lives in many different respects.

Diseases associated with air pollution have not only an important economic impact but also a societal impact due to absences from productive work and school.

Despite the difficulty of eradicating the problem of anthropogenic environmental pollution, a successful solution could be envisaged as a tight collaboration of authorities, bodies, and doctors to regularize the situation. Governments should spread sufficient information and educate people and should involve professionals in these issues so as to control the emergence of the problem successfully.

Technologies to reduce air pollution at the source must be established and should be used in all industries and power plants. The Kyoto Protocol of 1997 set as a major target the reduction of GHG emissions to below 5% by 2012 ( 123 ). This was followed by the Copenhagen summit, 2009 ( 124 ), and then the Durban summit of 2011 ( 125 ), where it was decided to keep to the same line of action. The Kyoto protocol and the subsequent ones were ratified by many countries. Among the pioneers who adopted this important protocol for the world's environmental and climate “health” was China ( 3 ). As is known, China is a fast-developing economy and its GDP (Gross Domestic Product) is expected to be very high by 2050, which is defined as the year of dissolution of the protocol for the decrease in gas emissions.

A more recent international agreement of crucial importance for climate change is the Paris Agreement of 2015, issued by the UNFCCC (United Nations Climate Change Committee). This latest agreement was ratified by a plethora of UN (United Nations) countries as well as the countries of the European Union ( 126 ). In this vein, parties should promote actions and measures to enhance numerous aspects around the subject. Boosting education, training, public awareness, and public participation are some of the relevant actions for maximizing the opportunities to achieve the targets and goals on the crucial matter of climate change and environmental pollution ( 126 ). Without any doubt, technological improvements makes our world easier and it seems difficult to reduce the harmful impact caused by gas emissions, we could limit its use by seeking reliable approaches.

Synopsizing, a global prevention policy should be designed in order to combat anthropogenic air pollution as a complement to the correct handling of the adverse health effects associated with air pollution. Sustainable development practices should be applied, together with information coming from research in order to handle the problem effectively.

At this point, international cooperation in terms of research, development, administration policy, monitoring, and politics is vital for effective pollution control. Legislation concerning air pollution must be aligned and updated, and policy makers should propose the design of a powerful tool of environmental and health protection. As a result, the main proposal of this essay is that we should focus on fostering local structures to promote experience and practice and extrapolate these to the international level through developing effective policies for sustainable management of ecosystems.

Author Contributions

All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.

Conflict of Interest

IM is employed by the company Delphis S.A. The remaining authors declare that the present review paper was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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Case study: Air pollution in New York City

By Matt Burdett, 2 January 2020

On this page, we look at New York City as a case study of air pollution in one city and its varying impact on people.

Introduction to air pollution in New York City

New York City has long had a problem with air pollution. In 1953, 1963 and 1966, high pressure reduced winds which normally moved polluted air from the city, resulting in widespread health issues and even some deaths. In the twenty first century, air pollution continues to cause health issues across the city, as shown on the maps below.

• Health problems from air pollution in New York City. Source: ( One NYC, 2018 , p190).

However, on a global scale New York City’s air pollution is currently quite low. This page will look at the factors that have led to this low level of air pollution and the impacts of these strategies.

• Brooklyn’s pollution is a problem, but is very mild compared to some other cities such as New Delhi in India. Source: Popovich et al., 2019 . Data reflects regional estimates by Berkeley Earth based on observations at ground-level monitoring stations.

Causes of pollution in New York City

New York City’s Environmental Protection agency identifies several different types of air pollution. While some types, such as sulfur dioxide, may be relatively low, others such as ozone can be high. Being aware of the different pollutants is also important because they are caused by different emitters. Knowing this can help to tackle the problem.

The types of air pollutant and their main sources are ( NYC Environmental Protection, 2019) :

• Fine Particulate Matter (PM2.5) – all types of combustion sources
• Nitrogen Oxides (NOx) – emission from vehicles
• Elemental Carbon (EC) – fossil fuel combustion, including diesel exhaust
• Sulfur Dioxide (SO2) – fossil fuel combustion at power plants and other industrial facilities
• Ozone (O3) – motor vehicle exhaust, industrial emissions, and natural sources

New York’s response to air pollution

New York City has introduced several steps such as congestion charging (from 2020 onwards), switching taxis to cleaner fuels, and changing the oils used in heating. These are part of a wider sustainability plan.

Sustainability planning frameworks

In 2007, New York City began its first sustainability plan, known as PlaNYC. To achieve clean air, it set out fourteen initiatives that would reduce PM2.5 emissions by 40%. These were in five broad areas ( Charles-Guzman, 2012 ):

• Reduce vehicle emissions from roads
• Reduce general transport emissions (including ferries, trains and so on)
• Reduce emissions from buildings
• Develop natural solutions, such as planting trees
• Engage in research to develop further understanding of air pollution in New York

In 2015, PlaNYC was taken over by One NYC. One NYC is a comprehensive planning document that looks at all aspects of New York City’s future, including the issue of air pollution. It includes the stated goal “New York City will have the best air quality among all large U.S. cities by 2030” ( One NYC, 2018 , p188).

Specific strategies

The strategies mentioned below are not necessarily mentioned in the One NYC plan for air pollution reduction, but are all strategies that are being used that will reduce the problem of air pollution.

• Congestion charging

A congestion charge is a payment made by drivers who want to enter the city centre. Similar schemes have been very successful in other cities such as London where, since 2003, drivers have avoided paying the charge by not entering (and therefore not polluting) the city centre, or switching to cycling. The result in London is a drop of about 30% of vehicles in the city centre ( Edmond, 2014 ).

New York City’s congestion charge began on 1 January 2019 for some commercial vehicles ( NYC Taxi and Limousine Commission, 2019 ) and covered all of southern Manhattan. It is being extended in 2020/2021 to cover all vehicles and will be the first such scheme in the United States ( Durkin and Aratani, 2019 ).

• New York City’s congestion charge for taxis and limousines. Source: NYC Taxi and Limousine Commission, 2019 .

Clean air taxi fuels

Vehicles are subject to national standards decided by the US Environmental Protection Agency, so New York City cannot impose its own emissions standards on private vehicles, However, the PlaNYC and One NYC plans both included plans to convert the city-owned or controlled vehicles (such as dustcarts, cleaning vehicles and emergency vehicles) to more fuel efficient sources which pollute less. By 2012, over 30% of the city’s taxis had been converted ( Charles-Guzman, 2012 ) and by 2017 there were over 200 electric vehicle charging stations in the city.

The result was that between 2007 and 2015 the “overall fuel efficiency of the medallion taxi fleet climbed from 15.7 to 33.1 MPG [miles per gallon], and corresponding estimates of nitrous oxide and particulate exhaust emissions declined by 82 percent and 49 percent, respectively” ( Columbia University’s Mailman School of Public Health, 2019 ).

Switch to more efficient heating oils in buildings

New York City gets cold in winter, and most buildings are independently heated using oil burning systems. In 2010, the City legislated to reduce the sulfur content of some of the types of fuel used, and in 2012 the City launched its ‘Clean Heat’ programme which offered advice and financial and technical assistance to help owners change their buildings to better sources of fuel. Between 2012 and 2015, over 6000 buildings were converted most buildings to more efficient sources of fuel. This is projected to reduce related hospital visits by 700 per year and avoid 300 premature births due to the associated air pollution. ( New York City Department of Health and Mental Hygiene, 2016 ).

• Planting trees

New York City’s ‘Million Trees Initiative’ aimed to plan trees in among the existing city infrastructure including in parks, as part of new developments, and on streets. The initiative has multiple aims including flood water management, but the top reason for planting is to reduce atmospheric pollution ( NYC Parks, n.d. ).

According to the Million Trees Initiative, “one tree can remove 26 pounds of carbon dioxide from the atmosphere annually, the equivalent of 11,000 miles of car emissions. Our trees remove about 2,200 tons of air pollution per year, valued at $10 million annually” ( Million Trees NYC, 2015 ). The aim to plant one million trees by 2017 was exceeded and they were planted by 2015 ( Dumplemann, 2019 ).

These initiatives appear to have worked. As the map below shows, in all but a few central areas (some of which are where congestion charging will be introduced in the 2020s) air pollution has decreased.

• Citywide improvements in air quality between 2009 and 2017. Source: NYC Health, 2019 a.

It is not only PM2.5 particles that have reduced. All of the main pollutants have decreased between 2009 and 2017 ( NYC Health, 2019b ):

• Fine particles (PM2.5) -30%
• Nitrogen Dioxide (NO2) -26%
• Nitric Oxide (NO) -44%
• Black Carbon (BC) -30%

Perhaps most successfully, the amount of sulfur dioxide has declined by 96%, mainly as a result of the new regulations on heating oils used in buildings.

Charles-Guzman, 2012. Air Pollution Control Strategies In New York City:mA Case Study Of The Role Of Environmental Monitoring, Data Analysis, And Stakeholder Networks In Comprehensive Government Policy Development. https://deepblue.lib.umich.edu/bitstream/handle/2027.42/94532/Kizzy%20Charles-Guzman%20practicum%20120312.pdf?sequ

Columbia University’s Mailman School of Public Health, 2019. Clean air taxis cut pollution in New York City. In ScienceDaily. https://www.sciencedaily.com/releases/2019/05/190529131221.htm Accessed 3 January 2020.

Dumpelmann, 2019. How a Massive Tree-Planting Campaign Eased Stifling Summer Heat in New York City. https://www.discovermagazine.com/environment/how-a-massive-tree-planting-campaign-eased-stifling-summer-heat-in-new-york-city Accessed 2 January 2020.

Durkin and Aratani, 2019. New York becomes first city in US to approve congestion pricing. https://www.theguardian.com/us-news/2019/apr/01/new-york-congestion-pricing-manhattan Accessed 3 January 2020.

Edmond, 2014. 4 bold new ways New York is going clean and green. https://www.weforum.org/agenda/2019/04/new-york-city-goes-green-meatless-congestion-clean-air/ Accessed 3 January 2020.

Million Trees NYC, 2015. NYC’s Urban Forest. https://www.milliontreesnyc.org/html/about/forest.shtml Accessed 3 January 2020.

New York City Department of Health and Mental Hygiene, 2016. New York City Air Quality Programs Reduce Harmful Air Pollutants. https://www.healthypeople.gov/2020/healthy-people-in-action/story/new-york-city-air-quality-programs-reduce-harmful-air-pollutants Accessed 3 January 2020.

NYC Environmental Protection, 2019. Air Pollution & Regulations. https://www1.nyc.gov/site/dep/environment/air-pollution-regulations.page Accessed 7 November 2019.

NYC Health, 2019a. Health Department Releases Report on Improvements in Citywide Air Quality. https://www1.nyc.gov/site/doh/about/press/pr2019/health-department-releases-report-on-air-quality.page Accessed 2 January 2020.

NYC Health, 2019b. The New York City Community Air Survey: Neighborhood Air Quality 2008-2017. https://nyc-ehs.net/besp-report/web/report/6 Accessed 3 January 2020.

NYC Parks, n.d. Street Tree Planting. https://www.nycgovparks.org/trees/street-tree-planting Accessed 3 January 2020.

NYC Taxi and Limousine Commission, 2019. New York State’s Congestion Surcharge. https://www1.nyc.gov/site/tlc/about/congestion-surcharge.page Accessed 3 January 2020.

One NYC, 2018. One New York: The Plan for a Strong and Just City. https://onenyc.cityofnewyork.us/wp-content/uploads/2018/04/OneNYC-1.pdf Accessed 2 January 2020.

Popovich et al., 2019. See How the World’s Most Polluted Air Compares With Your City’s.

https://www.nytimes.com/interactive/2019/12/02/climate/air-pollution-compare-ar-ul.html Accessed 2 January 2020.

Case study: Air pollution in New York City: Learning activities

• Briefly outline the history and causes of air pollution in New York City. [3]
• Briefly summarise the differences between the PlaNYC and One NYC frameworks for sustainability. [2]
• Clean air fuels
• Efficient heating oils
• Evaluate the success of these strategies. [6]

Other tasks

Does your nearest city have an air pollution problem? Does it have an air pollution strategy? Write to a local government representative suggesting what they could do regarding air pollution and why. You may like to check the current levels of air pollution in your nearest city using https://waqi.info/#/c/7.085/8.785/2.4z

© Matthew Burdett, 2020. All rights reserved.

All secondary material on this site is clearly referenced and may be subject to copyright restrictions by the original authors. All original material on this page is subject to copyright.

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Air pollution and human health in kolkata, india: a case study.

1. Introduction

2. study area, 2.1 sources of air pollution in kolkata, 3. database and methodology, 3.1. monitoring stations and criteria pollutants, 3.2. air quality assessment.

• Critical pollution (C): when EF is more than 1.5;
• High pollution (H): when the EF is between 1.0–1.5;
• Moderate pollution (M): when the EF between 0.5–1.0; and
• Low pollution (L): when the EF is less than 0.5.

3.3. Health Assessment

3.4. data analysis, 4. results and discussion, 4.1. concentration and trends of ambient air quality, 4.2. interpreting health outcomes of surveyed dispensaries in kolkata, 4.3. outdoor pollution-averting activities, 4.4. diseases analysis, 5. conclusions, acknowledgments, author contributions, conflicts of interest.

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Haque, M.S.; Singh, R.B. Air Pollution and Human Health in Kolkata, India: A Case Study. Climate 2017 , 5 , 77. https://doi.org/10.3390/cli5040077

Haque MS, Singh RB. Air Pollution and Human Health in Kolkata, India: A Case Study. Climate . 2017; 5(4):77. https://doi.org/10.3390/cli5040077

Haque, Md. Senaul, and R. B. Singh. 2017. "Air Pollution and Human Health in Kolkata, India: A Case Study" Climate 5, no. 4: 77. https://doi.org/10.3390/cli5040077

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Four IUCN economic case studies show the impacts of plastic pollution in the marine environment on biodiversity, livelihoods, and more in Africa and Asia

Research into the economic aspects of the Marine Plastics and Coastal Communities project, to contain and reduce plastic pollution in the ocean, delivers insight into the true costs of plastic pollution on communities, livelihoods, coasts, and the global ocean.

Photo: Adobe Stock Image

The objective

The Marine Plastics and Coastal Communities (MARPLASTICCs) project goal was to assist governments and regional bodies in Eastern and Southern Africa and Asia to promote, enact, and enforce legislation and other effective measures to contain and reduce plastic pollution in the ocean. Part of the research completed included defining an economic assessment approach and producing economics case studies that reflected the impacts of plastic pollution on the marine environment, on coastal livelihoods, and more.

National case studies

Four national level economic case studies are available: for Mozambique, South Africa, Thailand, and Viet Nam. The important economic sectors of fisheries and tourism were studied, using different lenses to examine how plastic pollution causes detrimental economic impacts at national and local levels. Each assessment differs and explores wide-ranging economic dimensions that should be considered when creating a national plan of action to mitigate marine litter and plastic pollution in the environment. From impacts upon export revenue, employment and food security, to the economic efficiency of beach cleaning in conjunction with deposit refund schemes, and the impact of ghost gear on fisheries, these four case studies take a reader into the true costs of plastic pollution on our global ocean and coastal communities.

Mozambique Economic Report

What is the impact of plastic pollution on fisheries – including the broader economic dimension relating to export revenue, employment, food security, and marine ecosystems, and biodiversity? This economic policy brief explains these impacts within the Republic of Mozambique.

South Africa: Efficiency of beach clean-ups and deposit refund schemes (DRS) to avoid damages from plastic pollution on the tourism sector in Cape Town, South Africa (2021)

What are the impacts of plastic pollution on tourism revenue and tourism employment? What is the efficiency of beach cleaning with the implementation of a DRS? What is the impact on employment after DRS implementation? This economic policy brief explains these impacts within the context of the city of Cape Town, South Africa.

Case study on net fisheries in the Gulf of Thailand

This issues brief presents the results of a study that estimated the impact of marine macroplastic on Thai net fisheries operating in the Gulf of Thailand. The study has estimated the reduction in the net fisheries’ revenue due to the plastic stock and annual flow into the fishing zone/Thai Exclusive Economic Zone (EEZ) (Gulf of Thailand).

The economic impact of marine plastics, including ghost fishing, on fishing boats in Phước Tinh and Loc An, Ba Ria Vung Tau Province, Viet Nam (2022)

What are the impacts of plastic pollution caused by abandoned, lost or otherwise discarded fishing gear (ALDFG), also known as ‘ghost gear’? What are the costs to biodiversity of ghost gear? This economic policy brief explains the impacts on fishing boats in Phước Tinh and Loc An, Ba Ria Vung Tau Province, Viet Nam.

On-the-ground work

The work IUCN is doing on the impacts of plastic pollution, especially on tourism, fisheries, and waste management aims to identify the plastic applications and polymers and the waste management gaps that are contributing to the global problem.

IUCN works on-the-ground with partners from NGOs, the private sector, and national governments, in order to determine the priority problems and the most effective interventions, to advise countries how to stop the problem within their specific national context. IUCN bring science and knowledge together with policy, for action, in this case economic policies can be examined for their role in dealing with plastic pollution.

As the world is now focused on the establishment of a global plastic pollution treaty , understanding the scope of the impacts and prioritising interventions – including economic interventions – will be needed.

Acknowledgments and Support

The Marine Plastics and Coastal Communities project (MARPLASTICCs), generously supported by the Swedish International Development Cooperation Agency (Sida), provided  support for the research and production of these Economic Case Studies.

For further information

• [email protected]

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Study tracks exposure to air pollution through the day

There are significant differences in how much people are exposed to air pollution, according to a new study co-authored by MIT scholars that takes daily mobility into account.

The study, based in the Bronx, New York, does not just estimate air pollution exposure based on where people live or work, but uses mobile data to examine where people go during a typical day, building a more thorough assessment of the environment’s impact on them.

The research finds exposure to particulate matter 2.5 microns or bigger rises by about 2.4 percent when daily travel patterns are taken into account.

“One of the main strengths of the study is that we try to improve the information we use, on the air quality side and also from the fine-grained estimation of people’s mobility,” says Paolo Santi, a principal research scientist at Senseable City Lab, part of MIT’s Department of Urban Studies and Planning (DUSP), and a co-author of a new paper detailing the study’s results. “That allows us to build trajectories of people’s movement. So, it was the first time we were able to combine these data to come up with a new measure of exposure.”

After all, people’s daily pollution exposure may be a complex combination of either living near, working near, or traveling by sources of particulate matter.

“People move around the city for jobs and education and more, and studying that is where we get this better information about exposure,” says An Wang of the Hong Kong Polytechnic University, another co-author of the study.

The paper, “Big mobility data reveals hyperlocal air pollution exposure disparities,” is published today in  Nature Cities .

The authors are Iacopo Testi of the Senseable City Lab; An Wang of Hong Kong Polytechnic University; Sanjana Paul, a graduate student in DUSP; Simone Mora, of the Senseable City Lab; Erica Walker, an associate professor at the Brown University School of Public Health; Marguerite Nyhan, a senior lecturer/associate professor at the National University of Ireland, University College Cork; Fábio Duarte of the Senseable City Lab; Santi; and Carlo Ratti, director of the Senseable City Lab.

To conduct the study, the researchers collected air pollution by mounting solar-power environmental sensors, including optical particle counters, temperature and humidity sensors, and GPS, on New York City’s civic services vehicles in operation in the Bronx.

“This strategy shows that cities can use their existing fleet as environmental sensors,” says Mora.

To measure how people moving through the Bronx are exposed to pollution in different times, the researchers used anonymized phone records of 500,000 different individuals and 500 million daily location records in New York.

The ground-level pollution data showed that the southeastern portion of the Bronx, where expressways and industries meet most intensively, has the most particulate matter.

The mobility data also revealed disparities in exposure when evaluated in terms of demographics, with income disparities present but disparities by ethnicity larger. For instance, some largely Hispanic communities have among the highest exposure levels. But the data also showed large differences in exposure levels within Hispanic communities.

Pollution exposure has significant implications from a health perspective, as Duarte notes. For instance, the Bronx has the worst air quality of any New York City borough, and, in turn, cases of asthma in the Bronx are 2.5 times higher in than any other borough.

“You see the consequences of exposure to pollution in the hospitalization of adults in the Bronx,” Duarte says.

As the researchers acknowledge, because the study was conducted in the fall of 2021, when the global Covid-19 pandemic was still affecting business and commuting, there may be slightly different mobility patterns in the Bronx today. Still, they believe their methods can give rise to additional future studies of the pollution exposure.

Ratti notes that mobile data, including pollution sensors on vehicles, can be used as “a huge monitoring system. It’s not expensive, we have the infrastructure in terms of cars and buses, and just putting sensors on them, you can have better air quality monitoring.”

And Wang notes that granular studies such as this one can be extended into studies that add in additional kinds of air-quality hazards, in addition to PM 2.5 particles.

“This actually opens the door for new analysis for many kinds of toxicity studies combined with exposure,” he says.

The study was supported by the MIT Senseable City Lab Consortium.

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EPA Releases Case Study on Air Pollution Reductions for the New York/New Jersey Harbor Deepening Project

PROJECT ACHIEVES PERMANENT AIR QUALITY BENEFITS FOR MILLIONS IN NEW YORK METRO AREA

September 15, 2021

NEW YORK — Today, the U.S. Environmental Protection Agency (EPA) released a new case study on the New York/New Jersey Harbor Deepening project, which highlights how coordination between federal, state, and local agencies led to lasting reductions in air pollution from marine vessels operating in one of America’s busiest waterways. As a result of this federal, state and local partnership, an estimated 2,000 tons of nitrogen oxide were prevented from polluting the air. Nitrogen oxide reacts with other chemicals in the air to form both particulate matter and ozone, which are harmful when inhaled due to effects on the respiratory system.

“Addressing air pollution at ports like the Port of New York and New Jersey is critical to protecting public health in the surrounding communities – especially those with environmental justice concerns – because poor air quality can aggravate respiratory diseases, particularly asthma,” said EPA acting Regional Administrator Walter Mugdan. “This case study shows how federal, state, and local agencies can effectively partner to find and implement solutions to reduce harmful air pollution at our ports.”   

The case study outlines how government agencies came together during the $2.1 billion channel deepening at the Port of New York and New Jersey to ensure Clean Air Act compliance while providing lasting clean air benefits. The multi-agency team, which included EPA, put together a strategy to offset the NOx emissions that generated from harbor deepening machinery with emissions reductions projects like upgrading old engines ferries and tugboats. They also developed a process for tracking emissions and implementing changes as needed over the 12-year-long project.

In total, project partners funded engine repowers and after treatment emissions controls on 36 tugs and ferries operating in the harbor. These cleaner engines offset all the emissions associated with dredging plus an additional 2,000 tons, or about the same as shutting down a local natural gas power plant for six years. The engine repowers proved very cost effective, coming in at just over $2,000 per ton of NOx reduced.

The multi-agency team is still active, and their process has been successfully applied to more than 10 additional projects. The model outlined in the case study can serve as an example for other large-scale projects to determine the proper tracking, analysis, and mitigation efforts needed to ensure regulatory compliance, expedient and cost-effective project implementation, and net environmental benefits beyond compliance.

Ports are critical for commerce, a keystone for economic growth, and play a significant role in the goods movement supply chain. Investing in clean port infrastructure and operations supports economic prosperity and reductions in emissions.  EPA’s Ports Initiative works to improve efficiency and reduce harmful air pollution at ports by advancing next-generation, clean technologies and practices, and collaboration among stakeholders including the port industry, communities, and all levels of government. To learn more about EPA’s Ports Initiative, please visit: https://www.epa.gov/ports-initiative .

To review the case study, please visit: https://www.epa.gov/ports-initiative/new-york-new-jersey-harbor-deepening-project-combines-infrastructure-improvements  

Follow EPA Region 2 on Twitter at http://twitter.com/eparegion2 and visit our Facebook page, http://facebook.com/eparegion2

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• Published: 29 July 2024

Big mobility data reveals hyperlocal air pollution exposure disparities in the Bronx, New York

• Iacopo Testi 1   na1 ,
• An Wang   ORCID: orcid.org/0000-0002-1874-2702 1 , 2   na1 ,
• Sanjana Paul 1 ,
• Simone Mora   ORCID: orcid.org/0000-0002-7991-1346 1 , 3 ,
• Erica Walker 4 ,
• Marguerite Nyhan   ORCID: orcid.org/0000-0002-4292-8232 5 ,
• Fábio Duarte   ORCID: orcid.org/0000-0003-0909-5379 1 ,
• Paolo Santi   ORCID: orcid.org/0000-0002-8942-8702 1 , 6 &
• Carlo Ratti 1 , 7  

Nature Cities volume  1 ,  pages 512–521 ( 2024 ) Cite this article

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Air pollution disproportionately affects socially disadvantaged populations. Our study bridges the existing gap in quantifying mobility-based exposure and its associated disparity issues. We combined the granular mobility of over 500,000 unique anonymized users daily and hyperlocal air pollution data in 100 × 100-m grid cells to quantify disparities in particulate matter exposure in a racially diverse and dense urban area of New York City. Our approach advances the study of exposure and its disparity from individualized exposure tracking to a population-representative scale. We observed apparently different spatial patterns between personal exposure and exposure disparities, noting that people from Hispanic-majority and low-income neighborhoods were those most severely and disproportionately exposed to fine particulate matter (PM 2.5 ) pollution. We reveal that race and ethnicity are much stronger indicators of exposure disparity than income. Our study further demonstrates that within-group variation contributes a major portion to exposure disparities, suggesting more granular mitigation plans are needed to target high-exposure individuals from socially disadvantaged groups in addition to generic air quality improvement.

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Acknowledgements

This study was funded by the MIT Senseable City Lab Consortium (Dubai Future Foundation, Toyota, UnipolTech, Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria, Volkswagen Group America, FAE Technology, MipMap, GoAigua, Shell, ENEL Foundation, Kyoto University, SMART – Singapore-MIT Alliance for Research and Technology, Weizmann Institute of Science, Universidad Autónoma de Occidente, Instituto Politecnico Nacional, Imperial College London, Università di Pisa, KTH Royal Institute of Technology and the AMS Institute). The study was conducted with the support of the Center for Climate-Smart Transportation, Johns Hopkins University, the NYC Office of Technology and Innovation, NYC Department of Health, NYC Department of Citywide Administrative Services, and the Spectus Social Impact team. Specifically, we thank S. Johnson from the New York City Department of Health, and E. Ilten and B. Lake from Cuebiq for their continuous help in air quality and mobility data acquisition and usage.

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These authors contributed equally: Iacopo Testi, An Wang.

Authors and Affiliations

Senseable City Lab, Department of Urban Studies and Planning, Massachusetts Institute of Technology, Cambridge, MA, USA

Iacopo Testi, An Wang, Sanjana Paul, Simone Mora, Fábio Duarte, Paolo Santi & Carlo Ratti

Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China

Department of Computer Science, Norwegian University of Science and Technology, Trondheim, Norway

Simone Mora

School of Public Health, Brown University, Providence, RI, USA

Erica Walker

School of Engineering and Architecture, University College Cork, Cork, Ireland

Marguerite Nyhan

Istituto di Informatica e Telematica, Consiglio Nazionale delle Ricerche, Pisa, Italy

Paolo Santi

ABC Department, Politecnico di Milano, Milan, Italy

Carlo Ratti

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Contributions

I.T. was involved in the conceptualization, writing of the paper, methodology and data acquisition. A.W. was involved in conceptualization, writing of the paper, methodology, data acquisition and supervision. S.P. was involved in the writing of the paper. S.M. was involved in supervision and project management. E.W. was involved in the methodology and writing of the paper. M.N. was involved in the methodology and writing of the paper. F.D. was involved in writing of the paper and supervision. P.S. was involved in the methodology, writing of the paper and supervision. C.R. was involved in supervision and funding acquisition.

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Correspondence to An Wang or Simone Mora .

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Testi, I., Wang, A., Paul, S. et al. Big mobility data reveals hyperlocal air pollution exposure disparities in the Bronx, New York. Nat Cities 1 , 512–521 (2024). https://doi.org/10.1038/s44284-024-00093-x

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Innovative lake pollution profiling: unveiling pollutant sources through advanced multivariate clustering techniques

• Published: 29 July 2024

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• Minakshi Mishra 1 , 2 ,
• Anupam Singhal 1 ,
• Srinivas Rallapalli 1 &
• Rishikesh Sharma 1  

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In many developed and developing nations, lakes are the primary source of drinking water. In the current scenario, due to rapid mobilization in anthropogenic activities, lakes are becoming increasingly contaminated. Such practices not only destroy lake ecosystems but also jeopardize human health through water-borne diseases. This study employs advanced hierarchical clustering through multivariate analysis to establish a novel method for concurrently identifying significantly polluted lakes and critical pollutants. A systematic approach has been devised to generate rotating component matrices, dendrograms, monoplots, and biplots by combining R-mode and Q-mode analyses. This enables the identification of contaminant sources and their grouping. A case study analyzing five lakes in Bengaluru, India, has been conducted to demonstrate the effectiveness of the proposed methodology. Additionally, one pristine lake from Jammu & Kashmir, India, has been included to validate the findings from the aforementioned five lakes. The study explored correlations among various physical, chemical, and biological characteristics such as temperature, pH, dissolved oxygen, conductivity, nitrates, biological oxygen demand (BOD), fecal coliform (FC), and total coliform (TC). Critical contaminants forming clusters included conductivity, nitrates, BOD, TC, and FC. Factor analysis identified four primary components that collectively accounted for 85% of the overall variance. Following identification of pollution hotspots, the study recommends source-based pollution control and integrated watershed management, which could significantly reduce lake pollution levels. Continuous monitoring of lake water quality is essential for identifying actual contaminant sources. These findings provide practical recommendations for maximizing restoration efforts, enforcing regulations on pollutant sources, and improving water quality conditions to ensure sustainable development of lakes.

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'Not here to be dumped on': Opponents of New Bedford trash facility want more public input

• South Coast Renewables plans to build a waste transfer station in the North End of New Bedford.
• The Conservation Law Foundation and public officials have urged the state to reject the plan over noise, traffic and pollution concerns.
• The Mass. Department of Environmental Protection has yet to make a ruling.

NEW BEDFORD — Saying New Bedford residents "are not here to be dumped on," environmental advocates and elected officials are calling for more local input on a waste transfer station proposed in the New Bedford Business Park.

The South Coast Renewables' facility, formerly known as Parallel Products , would process up to 1,500 tons of municipal solid waste per day, including construction and demolition waste, from its proposed 100 Duchaine Blvd. location.

The nonprofit environmental advocate Conservation Law Foundation, which opposes the facility, along with public officials and environmental groups sent a letter to the MassDEP on Monday urging the department to take steps to collect more public input, as well as to rule against its suitability for the site.

Alexandra St. Pierre, director of Communities and Toxics at CLF, said, “New Bedford’s residents are not here to be dumped on. Adding another waste facility without their input is like throwing their voices into the trash. The health and concerns of New Bedford residents must be prioritized.”

'It's really frustrating': Protesters take to New Bedford City Hall steps to denounce recycler-expansion deal

New Bedford residents concerned with truck traffic, noise, pollution

South Coast Renewables' project has drawn opposition from neighboring North End residents who are concerned with the truck traffic, noise and potential pollution from the facility.

Municipal solid waste from communities within the state would be sorted to remove recyclables before the remaining waste is transported out of state by rail and/or truck to be landfilled or incinerated, according to the proposal.

The Massachusetts Department of Environmental Protection has not made a decision on the facility's suitability. A site suitability application was filed in February 2023. MassDEP's decision has been postponed at least six times , requesting and analyzing additional information.

A negative ruling would end the process. If MassDEP approves the site, the plan would go before the city Board of Health for consideration. That would include a public hearing process.

State looking at traffic impact studies

On July 10, MassDEP requested additional information on the traffic impact posed by the transfer station.

The Massachusetts Department of Transportation had reviewed traffic study information provided by the petitioner, and a peer review supported by project opponent South Coast Neighbors United.

MassDOT has provided that analysis, which South Coast Renewables is being asked to weigh in on.

Noise pollution: How loud will a solid-waste facility in New Bedford Business Park be? State is checking.

According to a MassDEP letter to South Coast Renewables, MassDOT "generally agreed" with comments from South Coast Neighbors United regarding the peer review.

However, MassDOT said it believed "that the overall traffic conditions at intersections near the property are not expected to substantially worsen in the study area as a result of the project, meaning there will not be a measurable change in the time through the Phillips Road intersection."

MassDOT said the study recommendations should be addressed as part of local or state permitting.

Resident health and concerns deserve priority

The Conservation Law Foundation's letter states that the community hasn't had a similar chance to provide additional input: "This imbalance must be addressed to ensure a fair process."

According to the CLF, "New Bedford already faces significant environmental burdens, including multiple hazardous waste sites and an active landfill. Adding another waste facility would only worsen these issues. Massachusetts has enough waste transfer capacity, with current facilities exceeding needs."

The letter asks MassDEP to organize a public listening session and extend the comment period by 30 to 60 days after South Coast Renewables submits its additional traffic review.

'A uniquely positive outcome': New Bedford reaches no-sludge deal with Parallel Products

A decision date has not been set

MassDEP acknowledged receiving the letter Monday, and is evaluating its next steps.

A decision date hasn't been set, and won't be until the agency's review is finalized, according to MassDEP.

Who signed on to the letter?

Elected officials who signed onto the letter included state Sen. Mark Montigny, state Rep. Paul Schmid, and city councilors Linda Morad, Naomi Carney, Brian Gomes, Shane Burgo, Ian Abreu, Leo Choquette, Maria Giesta, Shawn Oliver, Joseph Lopes and Ryan Pereira.

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Selin Presents Innovative Research on Mercury Pollution at International Conference in Cape Town

The 16th International Conference on Mercury as a Global Pollutant (ICMGP) took place in Cape Town, South Africa, from July 21 to 26, 2024. Established in 1990, ICMGP is the preeminent scientific event on mercury, significantly contributing to the Minamata Convention’s development.

Henrik Selin ,  Associate Professor of International Relations at the Frederick S. Pardee School of Global Studies, attended the conference to present research from a collaborative NSF-funded project. This project focuses on mercury use in artisanal and small-scale gold mining (ASGM) in Madre de Dios, Peru.

Selin’s presentation, “Using Systems Analysis to Evaluate Interventions Towards Sustainability in Artisanal and Small-Scale Gold Mining,” showcased the project’s innovative approach to understanding and addressing mercury pollution. The research, part of a broader NSF-funded initiative , uses a social, technical, and environmental systems perspective to analyze mercury use and human well-being in ASGM.

The ICMGP conference featured the latest scientific findings on mercury pollution and discussed their implications for international policy, particularly regarding the Minamata Convention’s implementation. A set of synthesis papers presented at the conference highlighted the critical role of mercury science in advancing the convention’s goals.

Selin’s research contributes to sustainability science by developing frameworks and insights for assessing integrated social-environmental systems. The project aims to inform initiatives to mitigate the environmental and social impacts of ASGM activities, including those under the global Minamata Convention on Mercury.

The NSF-funded project involves a multidisciplinary team, with Noelle Selin as the Principal Investigator and Ruth Goldstein, Steven Barrett, and Henrik Selin as Co-Principal Investigators. Their work combines atmospheric chemistry modeling, governance research methods, and ethnographic approaches to address key questions about mercury emissions, governance needs, and the social context of mercury use in ASGM regions.

Henrik Selin   has been at Boston University since 2004. His research and teaching focus on global and regional politics and policymaking on the environment and sustainable development. He is the author of   Mercury Stories: Understanding Sustainability through a Volatile Element ,  European Union Environmental Governance , and  Global Governance of Hazardous Chemicals: Challenges of Multilevel Management .  He is also the author and co-author of more than four dozen peer-reviewed journal articles and book chapters. He also  serves as Editor for the journal  Global Environmental Politics . Learn more about Professor Selin on his   faculty profile .

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Wildfire smoke is probably harming your brain

The Summary

• Studies have found that wildfire smoke negatively affects brain health.
• New research suggests that increased exposure to smoke is associated with a higher risk of dementia.
• As wildfires become more frequent and intense due to climate change, so does many people’s exposure to smoke — and the health risks that come with it.

Parts of California, Oregon and Montana are facing unhealthy levels of air pollution as several large fires blaze, including Northern California’s Park Fire , which has quickly ballooned into the fifth largest in the state’s history.The smoke poses a hazard for people in the immediate vicinity and even some far away, as wildfire smoke can travel hundreds or thousands of miles.

The tiny particles in that smoke aren’t just bad for your lungs — a spate of studies over the last few years have found that it also negatively affects brain health, raising the risk of dementia, cognitive challenges and mental health issues. 

“A lot of the research on wildfire smoke has historically focused on our lungs and our hearts,” said Stephanie Cleland, an assistant professor at Simon Fraser University who studies the health impacts of wildfire smoke. “A shift to focusing on cognitive outcomes and brain health is more recent.”

The latest addition to this body of evidence: Research presented Monday at the Alzheimer’s Association International Conference suggests that wildfire smoke could raise the chances of a dementia diagnosis.

The study analyzed the health records of more than 1.2 million older adults — ages 60 and up — in Southern California from 2009 to 2019. 

The researchers looked at where people lived to determine their exposure to fine particulate matter from wildfire smoke and other forms of pollution. Their results showed that the odds of getting dementia went up 21% for every additional microgram per cubic meter of fine particulate matter from smoke that participants were exposed to, on average, over three years. 

By contrast, the same increase in exposure to fine particulate matter from other sources — like cars or factories — was linked to a 3% increase in the odds of getting dementia.

The evidence is preliminary, but it makes the case that chronic exposure to wildfire smoke contributes to cognitive decline, said Dr. Holly Elser, the study’s author and a neurology resident at the Hospital of the University of Pennsylvania.

However, she said, “the threshold at which wildfire smoke starts to pose a risk for dementia is unknown.”

A study published in August similarly found that higher exposure to fine particulate matter from various sources, including wildfires, was associated with higher rates of dementia. 

Wildfires are becoming more frequent and intense due to climate change — which also increases many people’s exposure to smoke. The frequency of extreme wildfires more than doubled from 2003 to 2023, a recent study found .

Scientists think the reason wildfire smoke affects the brain is that the tiny particles within it can cross the barrier between the bloodstream and the brain, causing inflammation in the central nervous system. The particles might also travel directly to the brain via the nose. That, in turn, may affect people’s ability to think, learn or remember.Dementia isn’t the only potential consequence. A study in 2022 found that adults who’d recently been exposed to wildfire smoke performed worse on a brain training game that measured skills like memory, attention, flexibility, processing speed and problem solving.

“Within hours and days of exposure to wildfire smoke, we’re seeing significant reductions of people’s ability to pay attention,” said Cleland, one of the study’s authors.

Other research published the same year showed that exposure to wildfire smoke during the school year reduced students’ test scores relative to a year with no smoke.

“The more smoke you get, the worse you do on the tests,” said Marshall Burke, an associate professor of global environmental policy at Stanford University, who co-authored that study. “The effect on any individual student is probably pretty small, but if you add up across students and add up across schools, these amount to pretty large overall aggregate learning losses.”

Burke said he has some doubts about the dementia findings released this week, however, because wildfire smoke and other forms of pollution are “not an apples-to-apples comparison.” 

Elser acknowledged that many questions remain about smoke’s effects on the brain. It’s unclear, for example, whether smoke triggers dementia in healthy people or just among those who were already at risk. 

“It’s a really intriguing question, whether this is creating new dementia cases that never would have occurred, or whether it’s simply accelerating the onset of clinically apparent dementia,” she said.

Other lingering questions pertain to the link between wildfire smoke and mental health. A February study found that exposure to wildfire smoke in the western U.S. was associated with increased emergency department visits for anxiety. (Air pollution in general has been shown to be associated with depression and psychotic disorders like schizophrenia .) 

Elser said it’s possible that wildfire smoke changes the neurochemistry in people’s brains, which could drive depression and anxiety. But it’s also possible that the anxiety and stress of experiencing or living through a wildfire could independently lead to mental health challenges.

Other health consequences of wildfire smoke are much better understood. Scientists have known for decades that when fine particles from smoke are inhaled, they can travel deep into the lungs or enter the bloodstream, raising the risk of asthma, stroke, heart attack, lung cancer and low birth weight in newborns. 

Cleland said it’s not just people in fire-prone areas of the U.S. who have to worry about these risks, as evidenced by the Canadian wildfires last summer that blanketed parts of the Midwest and Northeast in smoke.

“Last summer completely changed our conversation around who’s exposed to wildfire smoke,” she said. “Oregon, California, Washington, British Columbia really experience a lot of wildfire smoke, but that doesn’t mean places like the Northeast U.S. or Ontario are immune.” 

To reduce exposure to wildfire smoke, experts recommend that people in areas with an Air Quality Index reading of 100 or higher avoid outdoor activities, close all windows, run indoor air filters and wear an N95 mask if they need to go outside. 

Aria Bendix is the breaking health reporter for NBC News Digital.