33 MODERN LIFE AND ATMOSPHERIC POLLUTION

Dr. Jitender Saroha

Objectives

define atmospheric pollution,
identify the natural and anthropogenic causes of atmospheric pollution,
explain the primary and secondary pollutants,
describe the effects of air pollution, and;
suggest measures to check atmospheric pollution

Contents

Introduction

Learning Objectives

Modern Life and Atmospheric Pollution

Atmospheric Pollution

Sources or Causes of Air Pollution

Natural Sources

Anthropogenic Sources

Primary and Secondary Pollutants

Effects of Air Pollution

Effects on Human Health

Effects on Vegetation

Effects on Material

Effects on Climate

Smog

Acid Precipitation

Ozone Depletion

Global Warming

Checking Air Pollution

Summary and conclusions

Multiple Choice Questions

Answers:

References

Web Links

Introduction

You very well know that Human beings have been interacting with their environment ever since their origin as a species. This interaction has been necessary for their survival as they depend for all their needs and wants on the natural environment. The humans have obtained countless benefits from the environment and in search for more and more advantages; they have often harmed it, both inadvertently as well as advertently. The intensity of man-environment interactions increased manifolds with transformation of traditional man into modernman. The modern life style has led to impoverishment of the environment in various ways and in some of the areas this impoverishment or environmental degradation has reached serious levels.

Atmospheric pollution has a close association with the modern way of living. The ever increasing population, affluence and technology have dramatically increased atmospheric pollution. In this module, focus in on atmospheric pollution and its relationship with modern way of living.

Modern Life and Atmospheric Pollution

Modern man is technologically and economicallyvery advanced. The technological advancement in health sector and improvement in transportation and communication resulted into sudden decline of mortality rates. Comparatively, the fertility rates remained high and world population entered into population explosion stage of demographic transition.In 1650, world population was about half billion,at present world population is 7.4 billion (Figure 1). Thispopulation explosion has resulted into dramatic increase in the needs and wants of people. To fulfill these demands of growing numbers exploitation of resources has taken place on unprecedented scale. The side effect of resource utilization is different types of pollution. The focus has remained on economic growth and increase in Gross Domestic Production (GDP). The surplus production has been possible at the cost of environmental degradation and depletion.

Figure 1: World Population and Production

Technological advancements have taken place in all aspects of our life. Use of technology has resulted into mass scale production. To distribute this mass scale output, different modes of transportation have evolved over the period of time. The twin process of industrialization and urbanization is torch bearer of modern life. Chimneys and belching forth smoke and soot became a symbol of growth and prosperity. Cities became symbols of modern life and development. In 1800, urban share was just 2.4 per cent; at present 54 per cent of the world population is urban (Figure 2). Cities are foci of exchange processes that are central to modern life. Due to clustering of population, industries and services mega cities and metropolis have become the main source of atmospheric pollution.

Figure 2: World Trend of Urbanisation, 1950-2050

Source:http://www.imf.org/external/pubs/ft/fandd/2006/09/images/picture7.gif

Industrial revolution, transport revolution and urbanization processes were fueled or energized dominantly by fossil fuels (Figure 3). Like population explosion the use of energy resources has also increased exponentially. In 1820, at world level energy consumption was about 20 exajoule (1EJ ═ 1018Joule) it increased five folds to 100 exajoule in 1950 and further about five folds by 2000. Therefore, economic advancement and modern life depend on intensive utilization of energy resources, so far especially fossil fuels. But all these advancements have resulted into atmospheric pollution which is evident from local to global level.

Figure 3: World Energy Consumption

Source:https://media.treehugger.com/assets/images/2012/03/world-energy-consumption-by-source.png.650x0_q70_crop-smart.png

Atmospheric Pollution

Atmospheric pollution is commonly known as air pollution. World Health Organization has defined air pollution as a situation in which the outdoor ambient atmosphere contains materials in concentration that are harmful to man and his surrounding environment. Air gets polluted through addition to it of gases, liquids and solid particles detrimental to human health.Air pollution is assuming serious proportions all over the world, because atmospheric pollution does not follow political boundaries.

Sources or Causes of air pollution

Air is never perfectly pure. There are many natural and anthropogenic sources of air pollution(Figure 4).

Natural Sources

The natural sources of air pollution, which have always existed, are volcanic eruptions, salt particles from breaking waves from coastal areas, pollen and spores released from vegetation, smoke from wildfires and windblown dust particles. Volcanic eruptions release sulphur, chlorine and ash particulates in atmosphere. Windblown dust is acquired usually from areas without vegetation or with little vegetation. Sandy deserts are the major source areas. Salt particles are acquired from coastal areas. Radon radioactive gas formed from decay of radium rocks can accumulate in buildings, especially in confined areas such as the basement. It is a health hazard and frequently causes lung cancer.Wildfires produce large scale smoke and carbon monoxide.

Figure 4: Sources of Air Pollution

Source: http://images.slideplayer.com/24/7253941/slides/slide_6.jpg

Anthropogenic Sources

The major man-made sources of atmospheric pollution are – burning of fossil fuels (firewood, coal, natural gas and petroleum products), vehicular exhausts, smokes of domestic and industrial sources, particulate matters, forest fires and stubble burning, and activities such as mining, quarrying and farming (Figure 4). Dust storms in USA during 1930s represent an example of natural air pollution accentuated by human actions. They occurred due to expansion of agriculture on marginal lands and faulty methods of cultivation. The severe droughts made the ploughed fields more vulnerable to prevailing strong winds.

About two centuries ago, the most noticeable source of air pollution was filthy factories which were representative of economic growth and industrial revolution.At present, most significant contribution comes from transportation sector.Power plants and factories continue to make important contributions.Burning of fossil fuels (coal and oil) for generating heat in industries, in thermal power plants and in internal combustion engines (automobiles, aircraft, ships, etc.) leads to release of carbon dioxide, carbon monoxide, oxides of nitrogen and sulpher, and particulate matter like soot or ash in the atmosphere.

In transport sector, the number of vehicles has increased exponentially especially in the last half century. Vehicles are a necessity as well as status symbol in modern life. On one hand they reduce the time and distance barriers,but on the other, vehicular exhaust contains all kind of air pollutants, like particulates, carbon monoxide, nitrogen oxides, sulphur dioxide, volatile organic compounds (VOCs), and lead and indirectly produces ozone.Automobiles are largest contributor to air pollution in cities like Delhi where they account for over 71 per cent of the total pollutants in air. Along with Delhi, nine more cities of India are in the list of 20 most polluted cities listed by WHO World Health Organisation (Figure 5).

Figure 5: Top 20 Most Polluted Cities of World

Source:http://www.hindustantimes.com/rf/image_size_640x362/HT/p2/2016/05/12/Pictures/_ff9528e6-1829-11e6-952f-d19f9bc24ed8.jpg

Traffic congestion due to increase in number of vehicles per unit area of roads, poor traffic management and lack of civic sense has intensified air pollution. It reduces speed and low speedvehicles burn fuel inefficiently and pollutes more per trip.Adulteration of petrol and diesel with lower-priced fuels for economic gains is common practice in South Asia, especially India. The adulterants increase emissions of harmful pollutants. Poor maintenance of vehicles and roads and old automotive technologies also contribute in vehicular pollution.

The key input of modern life is electricity. To run industries, to sustain services and to fulfil heating and cooling requirements for domestic and other purposes electricity is must. The overwhelming majority of electricity is still contributed by conventional power plants by burning fossil fuels. Thermal power plants produce a range of air pollutants like particulates (fly ash), sulphur dioxide, nitrogen oxides and hydrocarbons.

Industrial revolutionresulted in phenomenal growth of industries initially in MDCs (More Developed Countries) and later on in some of the developing countries like China and India. Industries provide employment opportunities and a great variety of value added goods required in the modern society. Industries emit all sorts of pollutants.Industrial plants that produce metals such as aluminium, zinc and steel, refine crude oil, manufacture cement, synthesize plastic, or make other chemicals are among those that produce harmful air pollution. Most of the industrial units emit pollutants continuously for long periods producing time specific and cumulative effects. Sometimes, industrial plants accidentally release huge amounts of atmospheric pollution. The leakage of poisonous gas MIC (Methyl Iso-cyanate) in the Bhopal Gas Tragedy of December 2-3, 1984 is well known.Therefore, it can be concluded that industries bring us economic prosperity, but their side effects include ill health and death also.

Forest fires, natural or man-made, also contribute in air pollution. Occasionally, however, they contribute in air pollution over large areas. Forest fires in Indonesia, Australia, California, USA and in Western Himalaya are common.Shifting cultivation or slash and burn agriculture also contributes in air pollution. Expansion of area under cultivation and faulty raw method of tillage resulted into dust storms in USA in 1930s. Fuelwood, cowdung, stubble and agricultural waste burning also contribute in air pollution, especially in rural India. Cigarette, biri, cigar and hooka smoking are great pollutants of air in urban as well as rural areas. They significantly contribute in indoor pollution and are harmful for active as well as passive smokers.

Primary and Secondary Air Pollutants

The pollutants added to the air directly from the identifiable sources that remain in the same chemical form as at the time of emission, are called primary pollutants(Figure 6). These are emitted directly from the sources.They include particulate matter (ash, smoke, dust and fumes); inorganic gases such as sulphur dioxide, carbon monoxide, nitrogen dioxide, ammonia and hydrogen fluoride; hydrocarbons and radioactive substances.

Conversely, the pollutants that undergo chemical changes in the atmosphere due to reactions among two or more pollutants are called secondary pollutants. These are formed in the atmosphere by chemical interactions among primary pollutants and normal atmospheric constituents.Pollutants such as sulphur trioxide, nitric acid, ozone, carbonic, and sulphuric acids are the major secondary pollutants.

Figure 6: Primary and Secondary Pollutants

Source:http://www.environment.scotland.gov.uk/media/26674/Sources-of-air-pollution_310314.png

The major air pollutants and their sources are listed in Table 1.

Effects of Air Pollution

Air pollutants have various kinds of effects on human life, the most significant being the effects on human health. The other effects of atmospheric pollution are on vegetation, materials and weather and climatic conditions.

Effects on Human Health: The primary and secondary air pollutants have serious harmful effects on human health. Respiratory diseases, lung problems, variety of cancers and eye, nose, throat and skin related problems are the most common adverse health effects of air pollution (Figure7).Air pollution is a major environmental risk to human health (Table 2). On the basis of severity of effects, magnitude of impacts and number of persons affected the pyramid of effects of air pollution is constructed (Figure8). By reducing air pollution levels, countries can reduce the burden of disease from stroke, heart disease, lung cancer, and both chronic and acute respiratory diseases, including asthma.

Figure7: Health Impacts of Air Pollution

Source:https://www.pca.state.mn.us/sites/default/files/styles/large_6_col/public/imageedit_3_8609922450.jpg?itok=f78dgsFO

Figure8: Pyramid of Effects of Air Pollution

According to the new WHO air quality model 2016, 92% of the world population lives in places where air quality levels exceed WHO standards.In 2012, the estimated number of deaths associated with indoor and outdoor air pollution was about 7 million (11.6% of all global deaths), in almost equal shares. About 90 per cent of these deaths were reported from low and middle-income countries, especially from WHO identified South-East Asia and Western Pacific regions. Majority of these deaths (90 per cent) are because of non-communicable diseases – notably cardiovascular diseases, stroke, chronic obstructive pulmonary disease and lung cancer (Figure 9). These deaths reflect that the most vulnerable populations are – women, children and older adults.

Figure9: Impact of Air Pollution

Source:http://iasbaba.com/wp-content/uploads/2015/11/air-pollution-min.jpg

Effects on Vegetation: The effects of air pollutants on plants depend upon their chemical nature, level of concentration and exposure time. Sulphur dioxide, SPM (Suspended Particulate Matter) and photochemical oxidants are the principal pollutants which deserve prime significance as far as impact of vegetation and agriculture is concerned. Air pollutants commonly damage the leaf structure. Excessive dust and smoke retards the growth of plants. Ozone reduces plant growth and crop productivity (Figure 10). The oxides of nitrogen and fluorides also suppress plant growth and damage leaf tissue. They can reduce the crop yields. Hydrocarbons such as ethane causes premature leaf fall andshedding of flower buds.

Figure 10: Plant Damage by Ozone

Source:https://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/mdvegetables/AirPollution_Fig2_ProgressionOfOzoneDamage.jpg

Effects on Material: It is well known that air pollutants through physical and chemical processes damage materials. Sulphur dioxide, oxides of nitrogen and particulate matter are most destructive pollutants. The natural effects of corrosion and weathering are intensified by air pollutants. Acid rain is in fact a cocktail of sulphuric acid and nitric acid. Sulphur dioxide and nitrogen dioxide affect fabrics, leather, paint and building stones. Carbonate-based-stones, particularly, suffer severe erosion because of acid rains. This phenomenon is known as stone-leprosy. Historical and heritage buildings have been severely affected by pollutants such as oxides of sulphur and nitrogen (Figure11).

Figure11: Impact of Air Pollution on Taj Mahal

Source:https://image.slidesharecdn.com/climatechangeimpactonheritagebuildingsmdsunivconference1-100118031154-phpapp02/95/climate-change-impact-on-heritage-buildings-mds-univ-conference-1-7-728.jpg?cb=1263784362

Effects on Climate

Smog: The word smog is combination of smoke and fog. It was coined to describe London Smog in 1952. The photochemical transformation of primary pollutants into secondary pollutants results into formation of smog (Figure 12).The primary pollutants mainly include nitric oxide, carbon monoxide and various unburned hydrocarbons from urban and industrial sources.Nitric oxide emitted in air is quickly oxidized to nitrogen dioxide. Solar ultraviolet radiation causes photochemical decomposition of NO2 into NO and O. Monatomic oxygen (O) then joins natural oxygen (O2) to form ozone (O3).The adverse effects of smog are not limited to local environment but to faraway places as well. Smog is harmful to humans, vegetation and materials.

Figure 12: Smog on December 08, 2013 at Lianyungang in Beijing, China

Source: http://www.ibtimes.com/china-pollution-outdoor-activities-suspended-beijing-schools-new-smog-alert-2213153

Acid Precipitation:It is the result of large scale burning of fossil fuels in vehicles, power plants and industries. As a result millions of tons of sulfur and nitrogen oxides are released into the atmosphere. Some of these pollutants through complex chemical reactions get converted into acids and fall on surface as rain or snow. This is known as wet deposition. By contrast, in dry areas the acid-producing chemicals are incorporated into dust and smoke and settle on ground as dry deposition. These dry deposits are washed by occasional rains resulting into acidic surface runoff.In highly urbanized and industrialized areas acid rains have become common. Northern Europe and eastern North America receive widespread acid rain. The most well known damaging effect of acid rain is elimination of fishes, from manylakes and there transformation to dead lakes, in Scandinavia and eastern North America.

Ozone Depletion: In modern life, CFCs have played significant role as refrigerants, solvents, propellants and retardants. These compounds are readily liquefied, relatively inert, non-toxic, non-combustible and volatile. In addition,large scale combustion of fossil fuels, increased use of nitrogen fertilizers in modern agriculture and modern supersonic jet planes have increases nitrogen oxide and other oxides of nitrogen in air. In photochemicalprocess,nitric oxide and CFCs with release of chlorine and bromine start ozone depletionin the stratosphere. Due to urbanization, industrialization and globalization the abundance of ozone depleting substances increases dramatically (Figure13). In 1985, ozone hole formation was reported by Farman et el.

Montreal Protocol 1987 on Ozone Depleting Substances is a legally binding international effort to address this problem.

Figure 13: Greenhouse Gases and Ozone Depleting Gases

Source:https://upload.wikimedia.org/wikipedia/commons/b/bb/Major_greenhouse_gas_trends.png

Global warming: Modern life style is the main cause of global warming. Population explosion, exploitation of resources, burning of fossil fuels, urbanization, industrialization and consumerism have resulted into increased share of green house gases like carbon dioxide, methane, nitrous oxide, tropospheric ozone and CFCs/HCFCs (Table 3). The enhanced green house effect has resulted into global warming. Measurements of trace green house gases in the composition of atmosphere show increased share mainly with the beginning of industrial revolution. The burning of fossil fuels in heating, transportation and industrial activities is the primary reason for this trend. Extension of agriculture and intensive agriculture has also contributed significantly. The primary sources of carbon dioxide are burning of fossil fuels, deforestation and forest fires. The concentration of methane has more than doubledthe pre-industrial level and isstill increasing (Figure 13). It is due to increase in area under paddy cultivation and increase in cattle population. Methane is produced by anaerobic bacteria in wet places such as swamps, bogs, wetlands, flooded paddy fields and the guts of grazing animals like sheep and cattle. Methane is also released in coal mines and in drilling of crude oil and natural gas. Nitrous oxide (N2O) originates primarily from microbial activity in soils and in oceans. Other anthropogenic sources are nitrogen fertilizers, fuel and biomass burning. CFCs were first produced in the 1930s for their multiple uses. As a result of the Montreal Protocol agreements to curtail production CFCs and use substitutes they have stabilized. Their substitutes HCFCs have a large green house potential.

Table 3: Anthropogenically Induced Green House Gases

Source: Barry and Chorley (1998), p-7 and Strahler and Strahler (1992) p-69 and Figure 13.

Checking Air Pollution

Air pollution can be prevented and controlled through legal and technological interventions with people participation. The legal approach focuses on the establishment of air quality standards. Anti-air pollution laws have been introduced worldwide during the second half of the 20th century. For instance, India enacted the Air (Prevention and Control of Pollution) Act in 1981 followed by another important enactment that of Environment (Protection) Act, 1986. Many of the once-polluted cities and industrial regions now have relatively clean air due to these legislative measures. These measures are related to emission norms and standards, fuel and lubricant quality specifications, alternative fuels and land use planning.

The best strategy is to prevent pollution of air. The magnitude of air pollution can be controlled and reduced by following preventive measures such as – use of less energy, more efficient utilization of energy, shift on non-conventional environment-friendly sources of energy, proper land use planning to restrict and control location of industries, installation of industries subject to environmental safeguards, creation of green belts around urban and industrial areas, maintenance of roads and management of traffic.

Use of smarter technologies in vehicles, households, industries and power plants ensures pollution control and prevention. Use of taller chimneys, removal of pollutants from fuel like lead-free gasoline, use of catalytic converters, filters, scrubbers, settling chambers and electric precipitators, proper treatment of sewage and other wastes before disposal, use of chemical processes like – absorption, adsorption and condensation to remove pollutants at source,

The use of precipitators can reduce the problems caused by thermal power plants, use of environment friendly fuels like CNG and LPG can help checking vehicular pollution. Better maintenance of machines and proper lubrication can reduce wear and tear of machines and thus reduce metallic particles in air. In addition to legislative and technological measures public awareness and participation play a significant role in prevention and control of air pollution. As atmospheric pollution does not follow political boundaries, international co-operation is required. One successful and motivating example is ratification of Montreal Protocol on Ozone Depleting Substances by all 197 UN member States.

The basic requirement to tackle air pollution is spatio-temporal data base. In India in 1984Central Pollution Control Board (CPCB) started National Ambient Air Quality Monitoring (NAAQM) programme which was subsequently renamed as National Air Monitoring Programme (NAMP). Among other things, the programme determines the status and trends of ambient air quality to ascertain whether the prescribed ambient air quality standards are violated. The programme also focuses on assessment of health hazard and damage to materials due to pollution. CPCB has launched the National Air Quality Index (AQI) in 2015. The motive is to provide information to public on the status of ambient air quality of selected cities regarding eight pollutants – sulphur dioxide, nitrogen dioxide, lead, ozone, PM10, PM2.5, carbon monoxide and ammonia.

Summary and Conclusions

Atmospheric pollution has a close association with the modern way of living. The ever increasing population, affluence and technology have intensified atmospheric pollution. The population explosion has resulted into dramatic increase in the needs and wants of people. To fulfill these demands of growing numbers, exploitation of resources has taken place on unprecedented scale. Burning of fossil fuels is the most important air pollutants source. The twin process of urbanization and industrialization intensified atmospheric pollution. Expansion of agriculture and intensive agriculture (green revolution) and livestock rearing, deforestation and forest fires have also contributed significantly in air pollution.

Primary pollutants and transformations as secondary pollutants have various kinds of adverse effects on human health, vegetation, materials and weather and climatic conditions. In 2012, the estimated number of deaths associated with indoor and outdoor air pollution was 6.5 million (11.6% of all global deaths). Acid rain, smog, ozone depletion and global warming are result of air pollution caused by modern way of living.

Air pollution can be prevented and controlled through legal and technological interventions with people participation. Policies and investments promoting cleaner sustainable transport, energy-efficient housing, power generation and manufacturing and better management of waste would reduce key sources of air pollution. The key aspects of this module are represented in summary in the following figure 14.

Figure 14: Air Pollution – A Summary

Source:https://pimg.tradeindia.com/01806474/b/1/Air-Pollution-Chart.jpg

you can view video on MODERN LIFE AND ATMOSPHERIC POLLUTION

References

Barry, R.G. and Chorley, R.J. (1998) Atmosphere, Weather and Climate, Routledge, London. Frederick, K.L and Edward, J.T. (2010) The Atmosphere – An Introduction to Meteorology, PHI Learning Private Limited, New Delhi.
Oliver, J.E and Hidore, J.J. (2003) Climatology: An Atmospheric Science, Pearson Education, Delhi.
Strahler, A.N. and Strahler, A.N. (2001) Modern Physical Geography, John Wiley and Sons, Singapore.

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