ATMOS
Atmospheric and Climate Science Lab.
Atmospheric Pollution and Rural Air quality
SIGNIFICANCE
Though clean air is a basic requirement of human health and well-being along with land and water. However, the air pollution not only poses a significant threat to human health and ecosystem but also a etc., climate, cryosphere, monsoon patterns, water cycle, agriculture and income. So air quality management and climate change mitigation are two inexorably linked environmental challenges of the twenty- rst century. The issue of air quality and atmospheric pollution need to be addressed through the consideration of energy production and consumption patterns globally, regionally and locally as the sources are mainly associated with these processes.
Effective mitigation of air pollution requires the understanding and quantifying the major contributing pollutant sources. Pollutants either be emitted directly or formed through photo-chemical reactions in the atmosphere by naturally or anthropogenic processes. Directly emitted pollutants can be managed by reducing their emissions, although source identification is challenging. The concentration of air pollutants depends not only on the quantities that are emitted from the polluting sources, but also on the ability of the atmosphere to either absorb or disperse such emissions through dynamic processes. Management of second type pollutants is more complex and intriguing because of their relationships to emission sources which may not be readily apparent and response to emission reductions may not be proportional. Studies show that the atmospheric pollutants contribute to climatic and cryospheric changes through their effects on solar radiation and the albedos of snow and ice surfaces.
The atmospheric pollution, climate change and cryospheric changes are closely related and necessary to be investigated in a coupled and integrated framework is our prime interest. The impact of air pollution at local, regional and global level has to be determined which are governed by different dynamic processes of emission and/or formation, transport, and removal and/or destruction processes. Addressing them in a coordinated manner can simultaneously slow down the rate of climate change and protect human health and ecosystems, including agriculture. Yet, air pollutants and greenhouse gases (GHGs) and their impacts are often considered independently in both scientific and policy spheres, but a recent model study says that with- out reductions in greenhouse gas emissions, air pollution and extreme weather will intensify in the 21st century.
Though the connections between greenhouse gases, climate change, and air pollution is very complex, they need to be investigated in a coupled and integrated framework is another important subject of research.
A strong group of researchers are involving in this field with well equipped facilities at the Atmos lab, CORAL IIT KGP in collaboration with IITM Pune, CSIR NPL, CNRS, Univ Belgium, Uni Bremen based on following resources:
Data Used: Satellite data: MODIS, INSAT, MOPIT, TROPOMI, GOME, MISR etc. Reanalysis Data: MERRA2, CAMS, ERA 5 etc. Ground observation data: CPCB, AERONET, Ozonesonde etc.
Platform: NASA (JPL), NOAA, ISRO, CPCB, NCEP, ECMWF etc.
MODEL: WRF-Chem, CHIMERE etc.
The team mainly focused on analyzing AOD, BC, PM, OC, SO2, NO2, CO, Tropospheric Ozone in the region Antarctic (South Pole), Arctic (North Pole), HKH (Third Pole), South Asia and other parts of the globe and their association with climate change and impact of climate change on trace gases.
Atmospheric Pollution and Rural Air quality
What is atmospheric pollution?
Air pollution is the presence of one or more contaminants in the atmosphere, such as dust, fumes, gas, mist, odour, smoke or vapour, in quantities and duration that can be injurious to human health. The main pathway of exposure from air pollution is through the respiratory tract. Breathing in these pollutants leads to inflammation, oxidative stress, immunosuppression, and mutagenicity in cells throughout our body, impacting the lungs, heart, brain among other organs and ultimately leading to disease.
What are the sources of atmospheric pollution?
Pollution in the atmosphere comes from two sources: Natural and Man-made (anthropogenic) sources
(i) Natural Sources
Natural sources of pollution include gases emitted from the body functions of living things (Carbon dioxide from humans during respiration, Methane from cattle during digestion, Oxygen from plants during Photosynthesis) and dust blown by the wind from areas with little or no green cover.
Along with the release of polluted gases, smoke from forest fires, volcanic eruptions, etc. also ranks among the list of natural sources of pollution.
(ii) Man-made (anthropogenic) Sources
While looking at the man-made contributions towards air pollution, it can be further divided into:
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Outdoor pollution sources
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Indoor pollution source
Outdoor Pollution Sources
Power generation, transportation, agriculture/waste incineration, industry, and building heating systems are the main outdoor pollution sources. The predominant element is smoke. The smoke produced by several types of combustion, such as in industries, cars, furnaces, and biomass burning.
Methane is produced when waste is thrown in landfills, and it has various negative effects. The interactions of some gases and chemicals can also produce toxic vapours that are risky for the health of living beings.
Indoor Pollution Sources
In low- and middle-income countries, harmful pollutants are produced in low- and middle-income nations when fuels like dung, coal, and wood are burned in inefficient stoves or open hearths. These include methane, polyaromatic hydrocarbons (PAH), particulate matter (PM), carbon monoxide, and volatile organic compounds (VOC). Significant emissions of fine particles and other pollutants are produced even while burning kerosene in wick lamps. Every year, 3.8 million people die prematurely due to exposure to cooking fire smoke.The formation of toxic vapours by some gases and chemicals can also be damaging to the health of living beings.
What are the important atmospheric pollutants?
Many of these harmful substances are released into the atmosphere both naturally and as a result of human activity. Human activities are the main causes of air pollution in industrialised nations. Pollutants in the atmosphere can be created or exist naturally. Background pollution is the level of air pollution that is caused by naturally occurring factors, which can include plant pollens, wind-borne dust, volcanic ash, smoke or gas emissions from forest fires etc. Major sources of pollutants from human activity in both urban and rural areas include motor vehicles, municipal waste, the production of electricity, and the manufacture of goods.There are numerous pollutants, such as:
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Sulfur dioxide (SO2)
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Carbon monoxide (CO)
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Carbon dioxide (CO2)
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Nitrogen oxides (NOx)
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Volatile organic compounds (VOCs)
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Particulates (PM10, PM2.5 and PM1.0)
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Ozone (O3)
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Chlorofluorocarbons (CFCs)
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Unburned hydrocarbons (HFCs)
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Lead and heavy metals (Pb)
What are the important atmospheric pollutants and their health impacts?
Numerous negative health impacts are caused by air pollution. For six of the most prevalent air pollutants, referred to as "criteria" air pollutants (or simply "criteria pollutants"), the EPA has established national ambient air quality standards (NAAQS). These pollutants include carbon monoxide, lead, ground-level ozone, particulate matter, nitrogen dioxide, and sulphur dioxide. These contaminants are typically present in ambient air due to numerous, varied, and widely dispersed sources of emissions. The main goal of the NAAQS is to safeguard public health.
Health effects that have been associated with each of the criteria pollutants are summarized below:
Ozone:
Chemicals that are precursors to ozone creation can also be emitted by natural sources, including plants and trees. Ground-level ozone is created when pollutants from industrial facilities, electric utilities, and automobiles react. Contrary to the stratospheric ozone layer, which shields the globe from damaging solar UV radiation, ground-level ozone can be hazardous to human health. Short-term ground-level ozone exposure can have a number of negative consequences on respiratory health, including lung lining inflammation, decreased lung function, and respiratory symptoms like coughing, wheezing, chest discomfort, burning in the chest, and shortness of breath. Ozone exposure in the environment has been linked to the aggravation of respiratory conditions such bronchitis, emphysema, and asthma
Particulate Matter:
Effects associated with exposures to both PM2.5 and PM10-2.5 include premature mortality, aggravation of respiratory and cardiovascular disease (as indicated by increased hospital and emergency department visits), and changes in sub-clinical indicators of respiratory and cardiac function. Such negative health impacts have been linked to both short- and long-term PM exposure. Exacerbation of allergy symptoms, impaired lung function growth, and an increase in respiratory symptoms are all linked to exposures to PM2.5. People with lower socioeconomic position, children, older people, those who already have heart or lung disease (including asthma), and those with pre-existing conditions are among the populations most at risk for the negative effects of PM exposure.
Sulfur Dioxide:
Sulfur dioxide can be especially harmful to those who have asthma. When asthmatics exercise at a moderate intensity for a short period of time, they may experience breathing issues that are accompanied by symptoms like wheezing, chest tightness, or shortness of breath. Additionally, studies consistently show a link between brief sulphur dioxide exposure and an increase in respiratory symptoms in children, particularly in those with asthma or other long-term respiratory conditions.
Nitrogen Dioxide:
Nitrogen dioxide exposure has been linked to a number of adverse health outcomes, including respiratory symptoms, particularly in children with asthma, and respiratory-related Emergency room visits and hospital admissions, especially in children and older adults.
Lead:
The body's soft tissues, blood, and bones all acquire lead. Young children who are exposed to lead may experience neuro-developmental impacts such as decreased IQ and behavioural issues because lead can affect how the central nervous system develops in these youngsters.
Carbon Monoxide:
Exposure to carbon monoxide lowers the blood's ability to carry oxygen, which limits the amount of oxygen that reaches tissues and organs like the heart. People who already have one or more forms of heart disease may develop myocardial ischemia (reduced oxygen to the heart), which is frequently accompanied by chest discomfort (angina), when they exercise or are under additional stress. These people's bodies already have an impaired ability to adapt to the higher oxygen needs of exercise or exertion. Short-term CO exposure exacerbates this problem. As a result, it is determined that those who have angina or heart disease are more at danger from ambient CO. People with chronic obstructive lung disease, anaemia, diabetes, and those in the perinatal or geriatric life stages are other potentially at-risk groups. The foetal development stage may be one that is particularly susceptible to negative health impacts brought on by maternal exposure to some specific air pollutants.
The World Health Organization (WHO) estimates that air pollution kills close to seven million people annually. Currently, nine out of ten people breathe air that contains more contaminants than the WHO's recommended levels, with those in low- and middle-income nations suffering the most. Humans who are exposed to air pollution may experience heart and respiratory issues like pneumonia and asthma.
How are the air pollutants seasonally distributed in India and why?
Due to the chemical and physical characteristics of air pollutants, which vary substantially with time, place, meteorology, and the source of emissions, the distribution of air pollutants in India is seasonal. After the monsoon season, when crop residue burning predominates in many areas of Haryana, most pollutants reach their peak levels. When compared to the monsoon season, PM10 concentrations rose by 65-112% and PM2.5 concentrations by 131-147%. (Mor et al., 2021). According to a study by Pathak and Kuttippurath (2022), NO2 levels in rural areas of India exhibit notable seasonal variations, peaking in the winter (2.0 ×1015 molec./cm2) and falling in the monsoon (1.5 ×1015 molec./cm2) seasons.
The complex weather across the Indo-Gangetic plains contributes significantly to the observed seasonal cycle of air pollution in these cities, with wintertime highs (caused by high inversion) and summertime lows (due to rains). Due to the heavy agricultural activity and the existence of several fertiliser industries, the Indo-Gangetic Plains (IGP) is one of the largest and fastest-growing NH3 hotspots in the world, with a growth rate of +1.2% yr-1 in the summer (June-August: Kharif season) (Kuttippurath et al., 2020). According to a study on SO2 pollution improvements over India, SO2 levels are greater in the winter (December to February) and lower in the pre-monsoon (March to May) seasons (Kuttippurath et al., 2022).
What are the air quality standards in India?
The National Air Quality Index (NAQI) was established to inform the public about air quality. The public can use this index to learn how much pollution is there in the air around them on a daily basis. The AQI takes into account eight pollutants (PM10, PM2.5, NO2, SO2, CO, O3, NH3, and Pb), although it can only be calculated if data for at least three of those pollutants are available, one of which must be either PM2.5 or PM10. Six AQI classifications exist: Good, Satisfactory, Moderate, Poor, Very Poor, and Severe. Following are the AQI readings, accompanying ambient concentrations (health breakpoints), and likely health effects:
The government has also set a standard for permissible limits of these harmful pollutants as per the sensitivity of an area as mentioned below:
Why pollution studies are important?
Decades of research have shown that air pollutants such as ozone and particulate matter (PM) increase the amount and seriousness of lung and heart disease and other health problems. More research is required to fully comprehend how poor air quality, particularly among vulnerable communities, contributes to negative health effects and an increase in disease. People who live in places with high levels of air pollution, children, and the elderly are particularly vulnerable. The findings of these inquiries are put to use to support the nation's air quality requirements set out by the Clean Air Act and to advance public health.
People may experience the effects of poor air quality sometimes or more often throughout the course of a day. Seasonal air pollution, such as increased ozone during the summer or particulate matter from woodstoves during the winter, can potentially cause exposure to pollutants to last for several days, weeks, or even months. The effects of exposure to air pollution on health vary on its intensity, duration, and population-specific health conditions. Studies are required to further understand the duration of exposure and any potential risk accumulation.
Why the cities have more pollution?
Most pollutants, including PM2.5, PM10, NO2, CO, and O3, exceed the regulations. SO2 is the only pollutant that complies with national regulations. The percent contribution from various sources for each of these contaminants varies. The primary causes of air pollution, however, have been well-identified and are the same in all Indian cities: vehicle exhaust, large industries like power generation, small businesses like brick kilns, resuspended dust on the roads from traffic and construction, open waste burning, combustion of different fuels for cooking, lighting, and heating, and in-situ power generation using diesel generator sets. An important cause of air pollution in Indian cities is the year-round combustion of diesel, petrol, gas, coal, biomass, and waste and resuspended dust.
What are the important atmospheric pollutants and their health impacts?
Air pollution impacts everything and is bad for our health, and it has an adverse effect on the environment by obstructing sunlight, lowering visibility, creating acid rain, and impacts crops, forests, and wildlife. The entire globe is impacted by greenhouse gas pollution, which is the root of climate change. Many of the harmful health effects of air pollution that humans experience can also affect wildlife. The most frequent effects on animals are harm to their respiratory systems, while neurological issues and skin irritations are also frequent. When subjected to persistent air pollution, plants and crops grow less.
1. Global Warming
The immediate changes that the world is experiencing as a result of global warming are another direct effect of air pollution. Globally rising temperatures, rising sea levels caused by melting ice from colder places and icebergs, habitat loss, and displacement have already warned of imminent tragedy if preservation and normalisation measures are not done immediately.
2. Acid Rain
When fossil fuels are burned, harmful chemicals like nitrogen oxides and sulphur oxides are discharged into the environment. When it rains, the water droplets react with these contaminants in the air to generate acidic rain, which then falls to the earth. Humans, animals, and crops can all suffer significant harm from acid rain.
3. Eutrophication
The situation known as eutrophication occurs when a significant amount of nitrogen, which is present in some pollutants, develops on the sea surface, transforms into algae, and negatively impacts fish, plants, and animal species.
4. Effect on Wildlife
Just like humans, animals also face some devastating effects of air pollution. The presence of toxic substances in the air can drive certain wildlife species to relocate and alter their habitat. The sea animals may potentially be harmed by the poisonous chemicals that accumulate on the water's surface.
5. Depletion of the Ozone Layer
Ozone exists in the Earth’s stratosphere and is responsible for protecting humans from harmful ultraviolet (UV) rays. Due to the existence of hydrochlorofluorocarbons and chlorofluorocarbons in the atmosphere, the ozone layer on Earth is thinning. As the ozone layer deteriorates, it will emit dangerous rays that will be reflected back to earth and may result in issues with the skin and eyes. Crops can be impacted by UV radiation as well.
source: NASA:Ozone Watch
6. Global Dimming
High levels of particulate pollution from all types of burning reduces the amount of sunlight that reaches the surface and even changes the appearance of the sky. When less sunlight is available for photosynthesis, forests grow at a slower rate and crops are less productive. Hazy skies not only reduce visibility, but also impact the weather and even the climate.
7. Adding Too Much Nitrogen to the Land
The amount of nitrogen in soils is raised by fugitive ammonia (NH3) from agriculture and fugitive nitrogen dioxide (NO2) from vehicle, truck, and aircraft emissions. Nitrogen is necessary for plants to thrive, but too much nitrogen can cause some plants to grow more slowly while encouraging the growth of others, upsetting the balance of species in an ecosystem. Grasslands and other delicate habitats are being badly impacted by this disruption all around the world.
What can we do to improve air quality?
Small steps taken at individual level might prove to be helpful in reducing atmospheric pollution:
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Conserve energy - at home, at work, everywhere.
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Look for the ENERGY STAR label when buying home or office equipment.
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Carpool, use public transportation, bike, or walk whenever possible.
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Follow gasoline refueling instructions for efficient vapor recovery, being careful not to spill fuel and always tightening your gas cap securely.
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Consider purchasing portable gasoline containers labeled “spill-proof,” where available.
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Keep car and other engines properly tuned.
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Be sure your tires are properly inflated.
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Use environmentally safe paints and cleaning products whenever possible.
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Mulch or compost leaves and yard waste.
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Consider using gas logs instead of wood.
What are the data sources and important sites on air pollution information?
https://www.temis.nl/index.php
https://disc.gsfc.nasa.gov/
https://earthengine.google.com/
https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era5
https://modis.gsfc.nasa.gov/
https://gmao.gsfc.nasa.gov/reanalysis/MERRA-2/
http://www.tropomi.eu/data-products
How model do the air quality forecast?
There are models that estimate levels of air pollution and air quality, much like forecasting the weather. The complexity of many forecast models is higher than that of weather forecast models. These models simulate mathematically how airborne contaminants spread across the atmosphere. Forecasting air pollution is a beneficial investment at all scales—individual, local, national, and international. Accurate forecasting helps people plan ahead, decreasing the effects on health and the costs associated. If people are informed about fluctuations in the air they breathe, the impact of contaminants on health, concentrations likely to have negative consequences, and steps to reduce pollution. Additionally, because individuals desire to see changes in public policy and individual behaviour, it is more likely that these changes will be motivated.
Such awareness has the potential to create a cleaner environment and a healthier population. Early forecasting is also used by governments to create policies that lessen the severity of local pollution levels. Such forecast models are numerous and all demand greater sophistication than weather forecast models. These models simulate mathematically how airborne contaminants spread across the atmosphere.
Meteorological forecasting
The first step to an accurate air quality forecast is an excellent weather forecast. Meteorological (weather) forecasting can be categorized into three main categories: climatology, statistical methods and three-dimensional (3-D) models.
1. Climatology
The foundation of climatology is the idea that the past is a reliable predictor of the future. This approach might be relatively one-dimensional because it is dependent on the correlation between particular meteorological conditions and pollution levels. This approach is frequently broadened to take into account the comparison of pollution patterns to weather patterns. This method is seen as a tool to supplement other forecasting techniques because of its numerous drawbacks.
2. Statistical methods
The association between air quality and weather patterns can be quantified using statistical methods. The three most commonly used include:
• The Classification and Regression Tree (CART) is a tool for grouping data according to differences. Variables that are correlated with the amount of ambient pollution are found using software. Based on the weather and connected pollutant concentrations, the data is utilised to forecast concentrations.
• Regression analysis determines how different variables relate to one another. There are correlations found between pollution levels and meteorological data variables by examining historical data sets. A formula that can be used to predict future pollution levels is the end outcome.
• Pattern recognition and adaptive learning methods are used by artificial neural networks. Computer-based algorithms are created to mimic the capacity for pattern recognition in the human brain. Due to its multi-dimensional approach, this strategy may be the best one for predicting pollution.
The fact that the mechanisms affecting air quality are assumed to be stable is a drawback of the statistical methods discussed above. As a result, any significant changes in emissions or climate, whether short-term or long-term, will significantly reduce the accuracy of these methodologies. There are more sophisticated techniques that make an effort to accommodate for these shortcomings. The term "three-dimensional models" applies to them.
Three-dimensional (3-D) models
Three-dimensional models mathematically represent all the important processes that have an impact on outdoor air pollution levels. Three-dimensional models simulate the emission, transport, and transformation of air pollution by making use of several submodels, including:
• Emission model: Simulates the spatial distribution of emissions from both natural and human sources.
• Meteorological model: Creates a trajectory model to predict the ambient levels of pollution using the 3-D meteorological model and emissions data.
• Chemical model: Looks at the transformation of primary (emitted) pollution into secondary pollution to determine the outcome of the pollutant.
The accuracy of pollution forecasting methods is rising quickly and will keep doing so. Accurate and comprehensible air pollution predictions support public awareness campaigns, enable vulnerable people to make plans in advance, and give governments information for public health alerts. For scientists and academics, this is a fascinating new field with a bright future.
What are the important studies on global and Indian air pollution?
1. M. Pathak and J. Kuttippurath: Air quality trends in rural India: analysis of NO2 pollution using satellite measurements, Environmental Science: Processes & Impacts, doi:10.1039/D2EM00293K, 2022.
2. Kuttippurath, J., Peter, R., Singh, A. and Raj, S., 2022. The increasing atmospheric CO2 over India: Comparison to global trends. iScience, https://doi.org/10.1016/j.isci.2022.104 , 104863.
3. Kuttippurath, J., Patel, V.K., Pathak, M. and Singh, A., 2022. Improvements in SO2 pollution in India: role of technology and environmental regulations. Environmental Science and Pollution Research, doi:10.1007/s11356-022-21319-2 , pp. 1-13.
4. Gopikrishnan, G.S., Kuttippurath, J., Raj, S., Singh, A. and Abbhishek, K., 2022. Air Quality during the COVID–19 Lockdown and Unlock Periods in India Analyzed Using Satellite and Ground-based Measurements. Environmental Processes, 9(2), pp. 1-21. https://doi.org/10.1007/s40710-022-00585-9.
5. Singh, A., Abbhishek, K., Kuttippurath, J., Raj, S., Mallick, N., Chander, G. and Dixit, S., 2022. Decadal variations in CO2 during agricultural seasons in India and role of management as sustainable approach. Environmental Technology & Innovation, p.102498. https://doi.org/10.1016/j.eti.2022.102498.
6. Ardra, D., J. Kuttippurath, R. Roy, P. Kumar, S. Raj, R. Mueller and W. Feng: The unprecedented ozone loss in the Arctic winter and spring of 2010/2011 and 2019/2020, doi: https://doi.org/10.1021/acsearthspacechem.1c00333 , 2022.
7. J. Kuttippurath , K. Abbhishek , G.S. Gopikrishnan , M. Pathak: Investigation of long–term trends and major sources of atmospheric HCHO over India, Environmental Challenges (2022), doi: https://doi.org/10.1016/j.envc.2022.100477 .
8. Kumar P., J. Kuttippurath, P. von Gathen et al.: The increasing surface and tropospheric ozone in Antarctica and their possible drivers, Environmental Science and Technology, https://doi.org/10.1021/acs.est.0c08491 , 2021.
9. Kuttippurath, J and S. Raj: Two decades of aerosol observations by AATSR, MISR, MODIS and MERRA-2 over India and Indian Ocean, Remote sensing of Environment, doi:10.1016/j.rse.2021.112363, 2021.
10. Pandey, A., Brauer, M., Cropper, M.L., Balakrishnan, K., Mathur, P., Dey, S., Turkgulu, B., Kumar, G.A., Khare, M., Beig, G. and Gupta, T., 2021. Health and economic impact of air pollution in the states of India: the Global Burden of Disease Study 2019. The Lancet Planetary Health, 5(1), pp.e25-e38. https://doi.org/10.1016/S2542-5196(20)30298-9
11. Silva, R.A., West, J.J., Lamarque, J.F., Shindell, D.T., Collins, W.J., Faluvegi, G., Folberth, G.A., Horowitz, L.W., Nagashima, T., Naik, V. and Rumbold, S.T., 2017. Future global mortality from changes in air pollution attributable to climate change. Nature climate change, 7(9), pp.647-651. https://doi.org/10.1038/nclimate3354
12. Venter, Z.S., Aunan, K., Chowdhury, S. and Lelieveld, J., 2020. COVID-19 lockdowns cause global air pollution declines. Proceedings of the National Academy of Sciences, 117(32), pp.18984-18990.
https://doi.org/10.1073/pnas.2006853117
References
1. Mor, S., Singh, T., Bishnoi, N. R., Bhukal, S., & Ravindra, K. (2022). Understanding seasonal variation in ambient air quality and its relationship with crop residue burning activities in an agrarian state of India. Environmental Science and Pollution Research, 29(3), 4145-4158. https://doi.org/10.1007/s11356-021-15631-6
2. Pathak, M., & Kuttippurath, J. (2022). Air quality trends in rural India: analysis of NO2 pollution using satellite measurements. Environmental Science: Processes & Impacts. DOI: 10.1039/D2EM00293K
3. Kuttippurath, J., Singh, A., Dash, S. P., Mallick, N., Clerbaux, C., Van Damme, M., ... & Varikoden, H. (2020). Record high levels of atmospheric ammonia over India: Spatial and temporal analyses. Science of the Total Environment, 740, 139986. https://doi.org/10.1016/j.scitotenv.2020.139986
4. Kuttippurath, J., Patel, V. K., Pathak, M., & Singh, A. (2022). Improvements in SO2 pollution in India: role of technology and environmental regulations. Environmental Science and Pollution Research, 29(52), 78637-78649. https://doi.org/10.1007/s11356-022-21319-2
5. UCAR Center for Science Education:-- https://scied.ucar.edu/learning-zone/air-quality/effects-air-pollution#:~:text=Air%20pollution%20affects%20all%20things,change%2C%20affects%20the%20entire%20planet
6. CPCB:-- https://cpcb.nic.in/upload/NAAQS_2019.pdf
7. Aerosol and monsoon climate interactions over Asia
https://doi.org/10.1002/2015RG000500
8. Air pollution Summaries on scientific reports
https://www.greenfacts.org/en/digests/air-pollution.htm
9. Sulfur Oxides
https://www.ifc.org/wps/wcm/connect/fa942b47-b7f2-421c-a48a-c3b824dfc168/HandbookSulfurOxides.pdf?MOD=AJPERES&CVID=jqeERsg
10. WHO website
https://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health
11. EPA Website
https://www.epa.gov/clean-air-act-overview/air-pollution-current-and-future-challenges
12. Ozone FAQs
https://www.epa.gov/environmental-topics/air-topics
13. Particulate matter FAQs
https://www.epa.gov/technical-air-pollution-resources
14. Environment, Health and Safety Online (EHSO)
FAQs on Air Pollution
http://www.ehso.com/airpollutionfaqs.php
15. Air quality models:-- https://www.iqair.com/in-en/newsroom/can-air-pollution-be-predicted
