(8) Pollution

Air Pollution Causes More than 6 Million Deaths Worldwide (Video)

What is Air pollution?


Atmospheric Pollution

Earth’s atmosphere is a layer of gases that surrounds the planet, reaching a thickness of about 300 mi (480 km).

This same distance may be considerable to a human traveling by car, but relative to the infinite vastness of space, our atmosphere is vanishingly thin.

This thin blue line cocooning Earth, which is so apparent from orbiting spacecraft and which makes life on the planet possible, is susceptible to change and damage. Contamination of the atmosphere by noxious compounds has occurred ever since prehistoric peoples used fire. However, the tremendous growth in the use of machinery that began in the late eighteenth century spawned the growth of industry and increased air pollution.

A legacy of the twentieth century is the use of compounds such as chlorofluorocarbons (CFCs) in a variety of household and personal products. The escape of these compounds into the atmosphere has led to the depletion of atmospheric ozone (O3), which has increased the amount of damaging ultraviolet radiation reaching Earth’s surface. These and other human activities far outweigh natural forms of atmospheric pollution.

Historical Background and Scientific Foundations

Atmospheric pollution can occur naturally. For example, the Hawaiian volcano Kilauea spews out approximately 2,000 tons (1,800 metric tons) of sulfur dioxide (SO2) every day during eruptions. Even more spectacularly, the series of massive eruptions of the Krakatoa Volcano on August 27, 1883 propelled ash 50 mi (80 km) into the atmosphere. The ash restricted the penetration of sunlight to such an extent that the average global temperature the next year was up to 2ºF (1.2ºC) below normal.

Nonetheless, these and other natural causes of atmospheric pollution are nowhere near as influential as human activities, which have occurred for hundreds of thousands of years, ever since prehistoric peoples learned to use fire for cooking and warmth. Examination of ice cores recovered from the Greenland ice sheet has revealed higher levels of lead, mercury, and nickel beginning about 5,000 years ago, when mining and smelting of metal ores began in Europe.

Despite this long history of atmospheric abuse, the present problems with atmospheric pollution date from the end of the eighteenth century and early nineteenth century, the period that is known as the Industrial Revolution.

Then, a number of technological advances including the introduction of the steam engine spurred the growth of manufacturing plants in or near major cities (a source of cheap and abundant labor for the factories). The concentration of industries and their use of coal as the power source instead of flowing water increased air pollution.

Although the air in the atmosphere is still made up predominantly of oxygen and nitrogen, atmospheric data collected since the Industrial Revolution have shown that the content of other, so-called trace gases has changed. Furthermore, new compounds have appeared.

The best example are chlorofluorocarbons (CFCs), which are a product of twentieth century technology. The atmospheric release of CFCs and hydrochlororfluorocarbons (which are used in air conditioners, refrigerators, and aerosol cans), halons (an ingredient of fire extinguishers), methyl chloroform, and methyl bromide have depleted the level of the atmospheric gas called ozone. Ozone consists of three oxygen molecules. The gas is found mainly in an upper layer of the atmosphere called the stratosphere.

Ozone is able to absorb the ultraviolet (UV) wavelengths of sunlight. UV light has sufficient energy to penetrate into the upper layers of skin, causing sunburn and, more ominously, to break apart the chains of genetic material inside cells. This genetic damage can lead to the development of some cancers. UV light can also damage vision. CFCs and the other compounds chemically destroy ozone, allowing more UV radiation to reach Earth’s surface.

Scientists began to monitor atmospheric ozone levels in the 1970s. Over the next three decades, the declining levels of ozone were recognized. The decline is not evenly spread throughout the atmosphere. Rather, the depletion is more pronounced in some regions, in particular over the Antarctic as an ‘‘ozone hole.’’

Since the time of the Industrial Revolution, trace gases such as carbon dioxide (CO2), nitrous oxide (N2O), and sulfur dioxide (SO2) have built up in concentration in the atmosphere. These gases have been dubbed greenhouse gases because, analogous to the way a greenhouse traps the sun’s heat, they cause the heat from the sun to be retained by the atmosphere. The result has been the warming of the atmosphere that is popularly known as global warming.

Impacts and Issues

Human industrial activity is by far the greatest contributor to atmospheric pollution. According to the U.S. Environmental Protection Agency (EPA), approximately 6.5 billion lbs (3 billion kg) of toxic compounds (including 100 million lbs, or 45 million kg, of cancer-causing chemicals) are released to the atmosphere every year in the United States alone.

A recent illustration of the influence of human activity on atmospheric quality is Beijing, China. Satellite monitoring of China as part of the European Space Agency’s Dragon Programme has revealed that the development of Beijing into an industrially important mega-city containing over 10 million people and nearly three million vehicles has been accompanied by an accumulation of the planet’s highest levels of nitrogen dioxide.

This gas is a respiratory irritant and, paradoxically to ozone depletion higher in the atmosphere, causes ozone build-up near the ground, which triggers smog. Similar findings have been found over developing areas of India As much a concern as ozone depletion is, there is good news. The effect is reversible in the absence of the ozone destroying compounds. More than 165 nations are signatories to the Montreal Protocol, an international agreement drafted in 1987 that commits them to phase out the use of ozone-depleting substances according to a timetable.

Although some atmospheric pollution occurs naturally, the amount generated through human industrial activity has the greatest impact on the atmosphere, particularly in regard to global warming.

Words to Know

Chlorofluorocarbons: Members of the larger group of compounds termed halocarbons. All halocarbons contain carbon and halons (chlorine, fluorine, or bromine). When released into the atmosphere, CFCs and other halocarbons deplete the ozone layer and have high global warming potential.

Greenhouse Gases: Gases that cause Earth to retain more thermal energy by absorbing infrared light emitted by Earth’s surface. The most important greenhouse gases are water vapor, carbon dioxide, methane, nitrous oxide, and various artificial chemicals such as chlorofluorocarbons. All but the latter are naturally occurring, but human activity over the last several centuries has significantly increased the amounts of carbon dioxide, methane, and nitrous oxide in Earth’s atmosphere, causing global warming and global climate change.

Ice Core: A cylindrical section of ice removed from a glacier or an ice sheet in order to study climate patterns of the past. By performing chemical analyses on the air trapped in the ice, scientists can estimate the percentage of carbon dioxide and other trace gases in the atmosphere at that time.

Industrial Revolution: The period, beginning about the middle of the eighteenth century, during which humans began to use steam engines as a major source of power.

Ozone: An almost colorless, gaseous form of oxygen with an odor similar to weak chlorine. A relatively unstable compound of three atoms of oxygen, ozone constitutes, on average, less than one part permillion (ppm) of the gases in the atmosphere. (Peak ozone concentration in the stratosphere can get as high as 10 ppm.) Yet ozone in the stratosphere absorbs nearly all of the biologically damaging solar ultraviolet radiation before it reaches Earth’s surface, where it can cause skin cancer, cataracts, and immune deficiencies, and can harm crops and aquatic ecosystems.

Stratosphere: The region of Earth’s atmosphere ranging between about 9 and 30 mi (15 and 50 km) above Earth’s surface.



DiMento, Joseph F. C., and Pamela M. Doughman. Climate Change: What It Means for Us, Our Children, and Our Grandchildren. Boston: MIT Press, 2007.

Gore, Al. An Inconvenient Truth: The Planetary Emergency of Global Warming and What We Can Do About It. New York: Rodale Books, 2006.

Seinfeld, John H., and Spyros N. Pandis. Atmospheric Chemistry and Physics: From Air Pollution to Climate Change. New York: Wiley Interscience, 2006.


Chow, J. C., J. G. Watson, J. J. Shah, et al. ‘‘Megacities and Atmospheric Pollution.’’ Journal of the Air and Waste Management Association 54 (2004): 1226-1236.

Web Sites

‘‘Breath of the Dragon: ERS-2 and Envisat Reveal Impact of Economic Growth on China’s Air Quality.’’ European Space Agency, September 1, 2005. <http://www.esa.int/esaEO/SEMEE6A5QCE_environment_0.html> (accessed March 2, 2015).

‘‘The 500-Meter Wheeze: Will Air Pollution Affect the Athletes at the 2008 Olympics in Beijing?’’ Slate.com, October 25, 2007. <http://www.slate.com/id/2176636/nav/fix> (accessed March 2, 2015).

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(6) Pollution

Delhi's alarming pollution level can reduce life expectancy by three years: study (Video)

World’s Most Polluted City Urged To Close Schools On Bad Air Days



Pollution in New Delhi - Gate Monument

A hypothetical contaminated lake

Assume that tiny amounts of 20 different synthetic chemicals have been detected in a local lake. Each is present in an amount so tiny that it alone is highly unlikely to cause a problem, certainly not in the short run. Many of these chemicals are also found, likewise in tiny amounts in our bodies. Should we be concerned?

Possibilities that could increase your concern

1. Among the 20 contaminants are chemicals that are very similar to one another. Similar chemicals may exert toxic effects in similar ways and the levels of each, if added together, could potentially pose a problem. Organophosphate pesticides are one example.

There are many different organophosphates, but each exerts toxicity in a similar way. So, if several of the contaminants are organophosphates, the total concentrations added together may cause concern.

2. Even if none of the chemicals act similarly in the body, perhaps some combination of them could exert a synergistic effect, that is, one chemical could magnify the effect of another chemical out of all proportion to its concentration. Testing for synergistic effects among 20 chemicals is almost impossible because we could not reasonably test them in all possible combinations.

3. Species differ widely in their sensitivity to toxicants. One species may be many times more sensitive than another. And within any individual species, including humans, there is also a range of sensitivity.

Possibilities that could decrease your concern

1. Two chemicals may be antagonists, i.e., one may inhibit the toxicity of another, lessening the chance of an adverse effect. Basically, one chemical acts as an antidote to the other.

2. Hundreds or thousands of chemicals are naturally present in the water; some or many may be similar chemically to the synthetic contaminants.

3. Animal and human bodies deal with contaminants using biochemical pathways that evolved over millions of years to break down natural poisons in the environment. Our bodies have no way of knowing if a given chemical is natural or synthetic.

4. A quarter century ago, chemists probably couldn’t even have detected many of these chemicals. Only now with sophisticated analytical methods can we even know if there are chemicals that might be of concern.


1. (a) Possibilities that might increase your concern. Did any of these points increase your concern? Explain. (b) Possibilities that could decrease your concern. Did any of these points lessen your concern? Explain.

2. Even testing a few chemicals in mixtures for possible toxicity is complicated and expensive. However, it is possible to examine the effect of the contaminated water itself on aquatic life. This is called whole effluent toxicity.24 Does whole effluent toxicity reassure you as a logical way to test toxicity? Why?

3. With which of the following conclusions do you most tend to agree and why? (a) It is alarming that many synthetic chemicals are detected. Our health, our children’s health, and wildlife are likely affected. Let’s find the sources of the chemicals and stop further emissions. (b) We cannot worry about every low-level contaminant. We cannot reduce emissions to zero and it would be prohibitively expensive to even reduce them to near zero. And, quite often a synthetic chemical also occurs in nature as a natural chemical. Animals and plants have evolved protective means over eons of dealing with natural poisons, and most probably can manage the chemicals in this lake too. Taking a chemical off the market could pose other problems – the chemical that replaces it in an industrial process may also pose problems that are now unknown. Let’s devote our limited resources to higher-risk problems.

4. Think about air pollution in an agricultural setting and ponder a situation that occurs with increasing frequency as people move into areas previously devoted to farming. New residents may complain about farm odors when farmers spread sewage sludge on their fields as a fertilizer or soil amendment. Both State and US environmental agencies support spreading carefully treated sludge. But one complaining resident said, “The human body knows when something is not good for you. Sludge must be bad. It smells so bad, it can make you nauseous.” (a) Does the fact that sludge smells bad mean that airborne substances are present at a harmful level? Explain. (b) Before you can decide whether concerns are legitimate, what questions would you want answers to?

5. Another resident said, “When someone spreads sludge, you get flies in your house . . . It’s awful.” Do flies present a potential danger? Explain.

6. If you were thinking of moving into a rural area: (a) What questions would you want to ask? (b) Should sellers be required to provide you with information on sludge-spreading or similar operations around their homes?

7. Consider that you already live in a rural setting. (a) How would you react if a large industrial farm (one with thousands of pigs, cattle, or poultry crowded into a limited space) moved into your rural neighborhood? What would your environmental and health concerns be?

Degradation of global environmental health

At the Earth Summit held in Rio de Janeiro, Brazil, in 1992, the heads of 120 governments met together. Their mission was to decide how to deal with Earth’s environmental problems including climate change, air and water pollution, deforestation, and loss of biodiversity (extinction of species). One result was Agenda 21, a strategy for sustainable development or, as one participant phrased it, “a blueprint for how humankind must operate in order to avoid environmental devastation.”

In 1997, 158 governments gathered for an Earth Summit+5 to discuss progress, but they found that environmental conditions were worse. A Malaysian delegate exclaimed, “Five years from Rio we face a major recession . . . a recession in spirit. We continue to consume resources, pollute, and spread and entrench poverty as though we are the last generation on Earth.”

Yet again in 2002, governments gathered for a World Summit on Sustainable Development. Despite a continuing grim environmental picture, participants took a different approach: they recognized that environmental sustainability is not possible when great numbers of people lacked even basic amenities such as safe drinking water and sanitary facilities. One major outcome was that all 191 UN member states pledged to meet eight Millennium Development Goals by 2015. One goal was to cut extreme poverty in half while “ensuring” environmental sustainability.

Gross pollution often goes hand in hand with gross poverty.

Pollution in less-developed countries

Environmental degradation in impoverished countries, often called less-developed countries is, according to the Asia Development Bank, “pervasive, accelerating, and unabated”. In an Atlantic Monthly article, William Langewiesche describes one city, New Delhi, India, where “. . . the pollution . . . seemed apocalyptic.

The streams were dead channels trickling with sewage and bright chemicals, and the air on the street barely breathable.”Rivers in some cities are described as “open stinking sewers.”

The World Health Organization (WHO) tells us that 2.6 billion people have no access to hygienic toilets. They use buckets, bushes, ditches, or rivers; if lucky, they have latrines. More than a billion lack safe drinking water. The WHO estimates that at least 1.6 million lives are lost each year through lack of access to sanitation and clean drinking water. Millions more are left chronically ill from the water they must drink.

Millions of deaths result yearly from infections caused by eating contaminated food.

Just by breathing the air, children in a heavily polluted city such as New Delhi inhale the equivalent of two packs of cigarettes each day.

Living in rural areas may be worse: up to 3 million deaths result worldwide each year from air pollution; about half of these arise from intolerable indoor air pollution. This occurs because almost 90% of impoverished households burn straw, wood, or dried manure inside their homes for cooking and often for heating, with very poor ventilation. Women and children are most affected.

 The effects of pollution go beyond deaths to impacting people’s ability to live healthy lives. One illustration: almost half the world’s population, especially small children, may suffer from waterborne diseases.


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(5) Pollution

Major Air Pollutants (Video)

Table of Common Pollutants

Pollutants and Sources

What Are the Six Common Air Pollutants?


Pollutants can be transported in unexpected ways

The grasshopper effect

The “grasshopper effect” (also called “global distillation”) is a special case of pollutant fate and transport. The insecticide, dichlorodiphenyltrichloroethane (DDT) provides an illustration. If DDT is used in a Latin American country, it evaporates and prevailing winds blow it north. As DDT encounters cooler air, it condenses and comes to earth. On a warm day, it evaporates again. The process repeats itself, sometimes many times. Finally, in the far north, it is too cold for DDT to evaporate again, so it stays put – the Arctic is a sink for DDT and similar persistent organic pollutants (POPs).

The POPs in the Arctic accumulate in soils and water, enter the Arctic food chain, and build up in the fat of marine mammals. The Inuit, the Arctic’s indigenous people, eat the contaminated animals with the result that DDT builds up in their body fat to levels among the highest seen in the world. Worse, because DDT and other POPs concentrate in fat, high levels are found in the fatty portion of a mother’s milk. Thus, infants receive risky amounts of these pollutants as they nurse. Canada has been working to cut pollutant flow from the south and in 2008, there was good news. Canadian government studies indicate that levels of PCBs, DDT, and other POPs in the flesh of Arctic animals have either leveled off or begun to decline. This can probably be attributed to an international treaty that banned production and use of a number of POPs.

But, if the grasshopper effect totally explained DDT accumulation in the frozen North, then DDT should be evenly distributed across the Arctic. In actuality, Canadian scientists find hotspots. Sediments in certain ponds have concentrations of DDT, 60 times higher than at nearby spots serving as controls. Investigation revealed that contaminated droppings of migratory seabirds (large numbers of which nest on cliffs over the ponds) were responsible for these striking observations. How did this happen? The DDT originated in southern regions where it contaminates fish in coastal waters. Seabirds eating the fish also become contaminated.

Thereafter, the birds migrate to nesting sites over Arctic ponds where their DDT-contaminated droppings fall to ponds below. Those droppings are major sources of nutrition into Arctic pond ecosystems, promoting the growth of moss and plankton, which become contaminated with DDT. Insects eat the contaminated moss and plankton. They, in turn, are eaten by birds and other animals. Thus, these chemicals continue to spread in the food web and in humans. This is land-based bioaccumulation.

Pollutants in sediments often don’t stay buried

Sediments are composed of soil, silt, minerals, and organic materials that have been carried in rainwater runoff from surrounding land and paved surfaces into a lake, river, or other water body. By its nature, sediment is buried by additional incoming sedimentary material. Other pollutants are often buried within the sediments too – but they are not dependably buried.

▪ Bottom-feeding organisms may take in the pollutants, thus introducing them into the food web.

 ▪ Riverine and coastal area sediments are sometimes dredged. When that happens, contaminants are brought back to the surface along with the sediment.

▪Water currents, such as a strongly flowing river, also move sediments. Here, again, you see a situation where pollutants may not stay put.

Soil pollutants likewise move

Pollutants in soil also may not stay trapped. Water percolating through soil can carry pollutants down into groundwater. Rainwater can dissolve and carry off pollutants, including pesticides and fertilizers. Rainwater also erodes soil that may have pollutants absorbed within it.

The chemical fate of pollutants

Pollutants not only move. Their fate is often - as noted with acid rain precursors - to be converted into other chemicals, undergoing reactions in the atmosphere, water, and soil.

Organic pollutants

Especially in moderate and warm climes, organic pollutants can be degraded in water, soil, and the atmosphere to end products that are less risky than the parent compounds.

Microorganisms (fungi and bacteria) degrade organic wastes, including plant debris, animal remains, the organic material in trash, and also many individual organic pollutants. Microbes work in both water and soil. Microbial breakdown is a vital natural service: wastes and chemical pollutants would otherwise build up in the environment to intolerable levels.

▪ CO2 and water are the end products of microbial metabolism when oxygen is present. An organic substance degraded all the way to CO2 and water is said to be mineralized.

▪ Some microorganisms can degrade organic substances without requiring oxygen to do so. In that case, the most common end product is methane (“swamp gas”) as seen when microbial degradation occurs in the mud of rice paddies or marshes.

▪ Some synthetic organic chemicals have structures that make it very difficult for microbes to degrade them. Included among these substances are polychlorinated chemicals such as dioxins, DDT, and PCBs, which sometimes persist in the environment for many years and, in very cold climates, indefinitely.

▪ Other factors contribute to degrading organic substances too. Atmospheric oxygen reacts with many organic substances.

▪ Heat: the higher the temperature, the more rapidly organic materials break down. In very cold conditions, the Arctic and Antarctic, organics may persist for many thousands of years, becoming deeply buried in snow and ice.

▪ Sunlight, especially the strong ultraviolet radiation of summer, contributes to the breakdown of organic pollutants.

▪ Wave motion in water assists degradation by bringing pollutants to the surface, exposing them to sunlight, heat, and oxygen.

A chemical species, the hydroxyl radical contributes to the degradation of both organic and inorganic substances.

Overwhelming the process

These processes provide natural services that are very effective in degrading organic substances. However, human activities often overwhelm natural systems. Food-processors, tanneries, and paper mills are examples of facilities that, historically, released such large quantities of pollutants and wastes into rivers and lakes that natural processes could not degrade them all. Thus water quality was severely degraded.

Inorganic pollutants

Inorganic chemicals are not mineralized to CO2 and water – they are already mineral substances. Inorganic substances do undergo chemical reactions, but are not destroyed in the same manner as organic materials. Think about a metal. Box 1.2 noted the instance of metals burned to metal oxides. Such oxidation can also occur, albeit slowly, without combustion. You may have seen a reddish bridge: the color results from the oxidation of the iron in the bridge, that is, iron reacts with atmospheric oxygen to form reddish iron oxide.

But take a sample of that iron oxide and heat it to a high enough temperature: you recover the iron while driving the oxygen back into the air It too reacts with oxygen to yield sulfur dioxide. As with iron oxide, given proper conditions, both sulfur and oxygen can be recovered.

Pollution that devastates

Sometimes a pollution event is so tragic that it changes our way of looking at the world. The deadly explosion that occurred in Bhopal India is one such event. Union Carbide, an American-owned factory in Bhopal, manufactured the insecticide carbaryl. The process used methyl isocyanate (MIC), an extremely toxic volatile liquid, which reacts violently with water. Despite this, the factory lacked stringent measures to prevent water from contacting MIC. During the night of December 2, 1984, water entered a storage tank containing 50 000 gallons (189 000 l) of MIC.

▪ The Indian government later said that improper washing of lines going into the tank caused the catastrophe. Union Carbide claimed that a disgruntled employee deliberately introduced water.

 ▪ In any case, 25-40 tons (23-36 tones) of a deadly chemical vapor settled over half this city of 800 000. About 3400 people were killed overnight, and perhaps another 15 000 died from their exposure in the following days and years. Over 40% of the women, who were pregnant at the time, had miscarriages. Tens of thousands more remained chronically ill 20-years later with respiratory infections, eye damage, neurological damage, and other ills. The catastrophe was worsened because many people lived crowded close around the factory. Moreover, poisoned residents received little medical attention at the time of the accident, at least partially because physicians didn’t know what compounds were in the toxic cloud. Thus, it was difficult to know the best mode of treatment.

 ▪ Compensation came slowly. For many years, a Bhopal court had criminal charges pending against Union Carbide’s then Chief Executive Officer, accusing him of having consciously decided to cut back on safety and alarm systems as cost-cutting measures.

▪ In 1984, Union Carbide had almost 100 000 employees, but almost went out of business and, by 1994, employed only13 000. In 2001, Dow Chemical bought the remains of Union Carbide and, not surprisingly, found that it was now held responsible for this continuing tragedy.

Tiny levels of contaminants

Bhopal represents horrendous pollution. Its opposite, levels of pollutants so low that they are barely detectable, presents a quandary – are such levels risky? Modern analytical chemistry is so sensitive that synthetic organic chemicals can be detected almost anyplace – in soil, water, air, food, animals, plants, and in our own bodies. As one scientist commented, “The analytical science has advanced just astronomically.” So how are we to think about such situations?

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(4) Pollution

 Air Pollution Causes More than 6 Million Deaths Worldwide


What substances pollute?

Almost any chemical or material from either human or natural sources can pollute.

Natural pollutants

This text emphasizes anthropogenic pollutants (i.e., pollutants produced by human activity), but natural chemicals can also pollute. This happens dramatically when an erupting volcano spews out huge quantities of rocks, ash, chlorine, sulfur dioxide, and other chemicals. Other natural chemicals can pollute too, but sometimes human actions allow natural substances to reach dangerous levels as in the following illustrations:

1. Radon is a naturally radioactive chemical, a gas that arises from transformations occurring in underlying rocks and soil around the world as natural radioactive uranium decays. But levels of radon in outside air are low. It is when radon seeps up into – and concentrates in – human structures that problems may arise. The US EPA ranks radon, associated with human lung cancer, as second only to environmental tobacco smoke as an environmental health risk.

2. Arsenic is natural too and previously was not a problem to people in Bangladesh and India. Their problem had been drinking surface water that was badly contaminated with infectious microbes. To correct this, millions of boreholes were drilled to provide clean drinking water. Unfortunately, arsenic in the rock and soil dissolves into the water in those boreholes. The result has been a massive ongoing poisoning event in which millions suffer from arsenic poisoning.

3. Asbestos too, is natural. But, in El Dorado County, California, population growth led to homes being built in previously unoccupied regions, including areas rich in asbestos deposits. Now asbestos exposure has become a major concern. Chronic exposure also occurs in certain regions of Turkey where naturally high levels of asbestos have led to respiratory diseases and cancer. Up until recent decades, asbestos was also a workplace pollutant.

An introduction to pollutant types

Category Examples

Organic chemicals - Polychlorinated biphenyls (PCBs), oil, many pesticides

Inorganic chemicals - Salts, nitrate, metals and their salts

Organometallic chemicals - Methylmercury, tributyltin, tetraethyl lead

Acids - Sulfuric, nitric, hydrochloric, acetic

Physicala - Eroded soil, trash

Radiological - Radon, radium, uranium

Biological -Microorganisms, pollen

Acids, as well as physical and radioactive pollutants can be either organic or inorganic – sulfuric acid is inorganic, acetic acid (found in vinegar) is organic. Biological pollutants are mostly organic, but contain inorganic components.

Gasoline combustion

Gasoline is primarily composed of hydrocarbons (molecules containing hydrogen and carbon) plus small amounts of contaminants. During combustion, the hydrocarbons are converted into the products shown below, subsequently released in the vehicle’s exhaust. Notice that oxygen (O2) is involved in almost all of the reactions. Waste energy is released as heat.

During combustion, hydrocarbons react with atmospheric oxygen (O2) yielding the products shown:

* The carbon in hydrocarbons carbon dioxide (CO2, a gas)

* The hydrogen in hydrocarbons water (H2O)

Because combustion in a gasoline engine is far from 100% efficient . . .

Hydrocarbons + O2CO2 + H2O + incomplete products of combustion. These include carbon monoxide (CO), soot (fine black carbon particles), volatile organic chemicals (VOCs), and lesser amounts of chemicals including PAHs. (Burning gasoline in a laboratory in an enriched oxygen atmosphere, could force combustion to completion, i.e., to CO2+ H2O.)

The contaminants in gasoline also react with atmospheric O2 during combustion.

* Metals + O2 metal oxides, tiny particulate pollutants

* Sulfur + O2 sulfur dioxide (SO2), a gaseous pollutant

Gasoline has little nitrogen (N2). However, 78% of the atmospheric air in which combustion is occurring is N2. Most of this (>85%) is released unchanged in the car’s exhaust. However, some N2 reacts with atmospheric oxygen: N2 + O2 nitrogen oxides

A natural law tells us that matter is neither created nor destroyed. So we know that the hydrocarbons and other substances in gasoline do not disappear. They are converted to CO2, water, and pollutants. The O2 that reacted with substances in gasoline is conserved too, with most being converted to CO2.

Another natural law tells us that energy is neither created nor destroyed. As gasoline burns, only a small portion of its energy is actually transformed into mechanical energy to power the engine. The rest is “lost” as heat. But, the energy is dissipated, not “lost.” Under certain circumstances, waste energy can be captured and used.


1. Assume that a gallon (3.8 liters) of gasoline weighs ~6 pounds14 (2.7 kg). How then can 20 pounds (9.1 kg) of carbon dioxide be emitted per gallon of gasoline (in the car’s exhaust)?

2. (a) How does the sulfur in gasoline end up as sulfur dioxide? (b) The metals as metal oxides?

3. With the exception of water, all the chemicals in the exhaust of your car are pollutants, more than 20 pounds (9.1 kg) of pollutants. How important is this piece of information? Explain.

Pollutant sources

 “I am, therefore I pollute” is a statement applying to a multitude of processes:

▪ Motor vehicles including cars, buses, airplanes, ships, and off-road vehicles

▪ Chemical and petroleum refineries

▪ Manufacturing facilities

▪ Commercial operations including dry cleaners, bakeries, and garages

▪ Plants generating electric power by burning coal, oil, or natural gas

▪ Agricultural operations growing crops or raising animals

▪ Food processing operations

▪ Mining

▪ Construction and road building

 ▪ Military operations

 ▪ Forestry operations

▪ Municipal operations including drinking water and wastewater treatment, and road maintenance

 ▪ Activities occurring in commercial and municipal buildings, and in private dwellings including, e.g., consumer product use. As population grows, pollution grows. And in wealthy locales, consumption per individual typically grows over time too, and technologies become larger. Thus, without concerted effort to prevent it, pollution and other forms of environmental degradation will also grow.

Pollutant fate and transport

Pollutants move and are transformed Pollutants seldom stay at the point of release.

▪ Pollutants move, are transported, among air, water, soil, and sediments, and often food as well. They often move transboundary: across state and national boundaries traveling with air or water currents. Sometimes, biotransport occurs meaning pollutants are carried in body tissues of migrating animals such as salmon, whales, or birds, or are found in the droppings of migratory birds.

▪ The fate of pollutants: a pollutant is typically transformed into end products different than the chemical form in which it was initially emitted. It may be transformed into chemicals that are no longer pollutants as when biological matter is broken down by microorganisms and incorporated into normal biological material within these organisms. On the other hand, a molecule such as TCDD (“dioxin”) can take years, even decades to be transformed into harmless forms.

▪ The process leading to the final fate can be complex.

Air, soil, and water pollution is greatest at the pollutant source

Although pollutants move, their concentrations are higher near the emission source. Consider dioxins emitted as particulates from an incinerator. The highest fallout of the particulates onto vegetation, soil, and water occurs near that incinerator. However, some dioxins do not fallout, but continue traveling with air currents for long distances before settling out.

 ▪ Wherever they fall, they may contaminate forage or grain that is then eaten by cattle and other animals – and these animals absorb these fat-soluble chemicals into their fat. Humans eating fatty meat such as hamburgers then absorb dioxins into their own fat. Chemicals such as dioxins that move into an organism’s fat may stay for years. This is a temporary “fate.” Eventually, over years the dioxins are slowly broken down and move out of the body.

Some impacts of pollutants occur far from the source

If the amount of pollutant carried in wind or water currents remains high enough, the pollutant can have effects far from where it was emitted.

Water transport

In the year 2000 a Romanian mining operation spilled cyanide and hazardous metals into the Danube River, which joins the Tisza River flowing into Hungary and Yugoslavia. One Yugoslav mayor said that 80% of the fish in the Tisza near his town died. Another stated “The Tisza is a dead river. All life, from algae to trout, has been destroyed.”

▪ A few years earlier an accident at a Swiss facility washed large quantities of chemicals into the Rhine River. These were carried into France and Germany, killing fish and other aquatic life along the way.

Air transport

When a gaseous pollutant mixes evenly with the atmosphere, it can sometimes be carried worldwide. Major examples are stratospheric ozone depletion due to CFCs and global climate change due to CO2. And, because some of these pollutants have long lives, they build up in the atmosphere over time unless their emission sources are removed.

▪ What about pollutants that change their chemical form after emission? Sulfur dioxide and nitrogen oxides (acid-deposition precursors) mix evenly in the atmosphere too.

However, whereas CFCs and CO2 are stable in the atmosphere, sulfur dioxide and nitrogen oxides are transformed from gases into tiny particles. Particles are heavier than air and don’t mix evenly. Still, they can move hundreds, even thousands, of miles before the acid particles finish settling out onto land and water. Interestingly, although acid particles do not travel worldwide, their impact is global. This is true because acidic pollutants (most commonly emitted during the burning of fossil fuels) are released in so many places around the world.

Another characteristic of sulfur dioxide and nitrogen oxides is that they are inorganic chemicals and do not degrade in the same way as most organic pollutants do. Although only small quantities may settle out at any one spot, if emissions continue, the acids build up over time in soil and water. Acid originating in European countries harms forests and lakes in Sweden to the north. Japan’s environment is damaged by coal burning in China. There are other pollutants that also travel thousands of miles, sometimes worldwide, and sometimes have impacts at a far point from the source of emissions.

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(7) Air Pollution

Pollution (Land, Air and Water Pollution)


What Is the Scientific Consensus about Future Global Temperature Changes?

 To project the effects of increasing greenhouse gases on average global temperatures, scientists develop complex mathematical models to simulate interactions among the earth’s sunlight, clouds, landmasses, oceans, ocean currents, concentrations of greenhouse gases and pollutants, and positive (runaway) and negative (corrective) feedback loops within the climate system. Then they run these elaborate and continually improving climate models on supercomputers and use the results to project future changes in the earth’s average atmospheric temperature. Such models provide scenarios or projections of what is very likely (90–99% level of confidence) or likely (66–89% level of confidence) to happen to the average temperature of the lower atmosphere. How well the results correspond to the real world depends on the validity of the assumptions and variablesbuilt into the models and on the accuracy of the data used.

In 1990, 1995, 2001, and 2007, the Intergovernmental Panel on Climate Change (IPCC) published reports on how global temperatures have changed in the past and made forecasts of how they are likely to change during this century. According to the 2007 report, based on analyzing past climate data and using 19 climate models, it is very likely (a 90–99% probability) that human activities, led by burning fossil fuels, have been the main cause of the observed atmospheric warming during the past 50 years.

The 2007 report and recent runs of 19 different climate models suggest that it is very likely that the earth’s mean surface temperature will increase by 2–4.5 Co (3.6–8.1 Fo) between 2005 and 2100, with about 3 Co (5.4 Fo) the most likely rise, unless the world makes drastic cuts in greenhouse gas emissions from power plants, factories, and cars that burn fossil fuels. This is a major increase in such a short period. The lower temperature in this range is likely only if global greenhouse gas emissions fall 50–85% by 2050-an unlikely assumption.

There is overwhelming consensus among the world’s climate scientists that global warming is occurring at a rapid rate, that human activities are the major factor in this temperature increase since 1950, and that human activities will play an even greater role in the warming projected to take place during this century (Concept 15-3). Energy use accounts for about two-thirds of the CO2 emitted byhuman activities, followed by agriculture (14%) and deforestation and other forms of land use (10%). In 2007, the leaders of the American Association for the Advancement of Science (AAAS)-the world’s largest general science body-said that Global warming is not a theory; it is a fact based on a growing torrent of information . . . . The pace of change and the evidence of harm have increased markedly over the last five years. The time to control greenhousegas emissions is now. . . . Delaying action to address climate change will increase the environmental and social consequences as well as the costs.

The global warming hypothesis is based on very reliable science. The question now is, what do we do about it?

Critical Thinking

If projected temperature increases 15-C take place, list three ways in which this will affect your lifestyle.

Can the Oceans Save Us?

Scientists have identified a number of natural and human-influenced factors that might amplify or dampen projected changes in the average temperature of the atmosphere (Figure 15-C). The oceans, for example, help moderate the earth’s average surface temperature by removing about 30% of the excess CO2 pumped into the lower atmosphere by human activities. The oceans also absorb heat from the lower atmosphere and use currents to slowly transfer some of it to the deep ocean, where it is removed from the climate system for unknown periods.

We do not know whether the oceans can continue to absorb more CO2. But the solubility of CO2 in ocean water decreases with increasing temperature. Thus, if the oceans heat up, some of their dissolved CO2 could be released into the lower atmosphere-like CO2 is bubbling out of a warm carbonated soft drink. This could amplify global warming.

Scientific measurements show that the upper portion of the ocean warmed by 0.32–0.67 C° (0.6–1.2 F°) during the last century-an astounding increase considering the huge volume of water involved. According to a 2007 study of the vast Southern Ocean around Antarctica, led by researcher Corinne Le Quere, the ability of the oceans to absorb more CO2 from the atmosphere is weakening.

In 2005, the U.K. Royal Society reported that higher levels of CO2 in the ocean have increased the acidity of the ocean surface by 30% from preindustrial times and could reach very harmful levels by 2150. This happens because much of the CO2 absorbed by the ocean reacts with water to produce carbonic acid (H2CO3)-the same weak acid found in carbonated drinks. The scientists involved in this study warn that this may reduce the ability of the oceans to remove CO2 from the lower atmosphere and thus could accelerate global warming.

This increase in seawater acidity also threatens coral reefs and alters seawater life by impairing the ability of certain shellfish (including certain plankton and tiny snails) to produce shells, which like coral reefs, are made of calcium carbonate (CaCO3). You can see this effect by dropping a piece of chalk (made of calcium carbonate) in a glass of vinegar (a weak acid) and watching it rapidly dissolve.

Extensive loss of these forms of plankton would disrupt food webs, killing seals, whales, and fish and perhaps disrupting human food supplies from the ocean. This would also decrease the ability of such plankton to slow global warming by removing CO2 from the atmosphere.

Bottom line: Changes in the temperature and acidity of the oceans as a result of human activities are likely to accelerate global warming. There Is Uncertainty about the Effects of Cloud Cover on Global Warming A major unknown in global climate models is the effect that changes in the global distribution of clouds might have on the temperature of the atmosphere. Warmer temperatures increase evaporation of surface water and create more clouds. Depending on their content and reflectivity, these additional clouds could have two effects. An increase in thick and continuous clouds at low altitudes could decrease surface warming by reflecting more sunlight back into space. But an increase in

thin and discontinuous cirrus clouds at high altitudes can warm the lower atmosphere and increase surface warming. We need more research to understand which of these effects might predominate globally and in various parts of the world.

In addition, infrared satellite images indicate that the wispy condensation trails (contrails) left behind by jet planes might have a greater impact on atmospheric temperatures than scientists once thought. NASA scientists found that jet contrails expand and turn into large cirrus clouds that tend to release heat into the upper troposphere. If these preliminary results are confirmed, emissions from jet planes could be responsible for as much as half of the warming of the lower atmosphere in the northern hemisphere.

Outdoor Air Pollution Can

Temporarily Slow Global Warming Aerosols (microscopic droplets and solid particles) of various air pollutants are released or formed in the troposphere by volcanic eruptions (Core Case Study) and human activities. They can either warm or cool the air and hinder or enhance cloud formation depending on factors such as their size and reflectivity.

Most aerosols, such as light-colored sulfate particles produced by fossil fuel combustion, tend to reflect incoming sunlight and cool the lower atmosphere and thus temporarily slow global warming. On the other hand, a 2004 study by Mark Jacobson of Stanford University indicated that tiny particles of soot or black carbon aerosols-produced mainly from incomplete combustion in coal burning, diesel engines, and open fires-may be the second biggest contributor to global warming after the greenhouse gas CO2.

Climate scientists do not expect aerosol and soot pollutants to counteract or enhance projected global warming very much in the next 50 years for two reasons. First, aerosols and soot fall back to the earth or are washed out of the lower atmosphere within weeks or months, whereas CO2 remains in the lower atmosphere for about 120 years. Second, aerosol and soot inputs into the lower atmosphere are being reduced because of their harmful impacts on plants and human health-especially in developed countries. Some scientists have suggested using balloons, large jet planes, or giant cannons to inject sulfate particles into the stratosphere as a possible way to slow global warming by reflecting some of the incoming sunlight into space and cooling the troposphere. The effect might be similar to the estimated 0.5 C° (0.9 F°) cooling effect that lasted about 15 months from the 1991 volcanic eruption of Mt. Pinatubo (Core Case Study). Huge amounts of SO2 would have to be injected into the stratosphere about every two years at an average cost of about $1 billion a year-nearly 100 times cheaper than the estimated cost of cutting CO2 emissions.

Other scientists reject this idea as being too risky because of our limited knowledge about possible unknown effects. Such a scheme could increase ozone depletion by boosting levels of ozone-destroying chlorine in the stratosphere. This short-term technological fix could also destroy much of the life in the oceans and their ability to remove CO2 by allowing CO2 levels in the lower atmosphere to continue to rise and increase the acidity of the oceans. As the oceans become more acidic, they absorb less CO2, which can accelerate global warming. Plants Can Remove More CO2 from the Atmosphere but the Effect Is Temporary

Some studies suggest that larger amounts of CO2 in the lower atmosphere could increase the rate of photosynthesis in some areas with adequate water and soil nutrients.

This would remove more CO2 from the lower atmosphere and help slow global warming.

However, recent studies indicate that this effect would be temporary for two reasons. First, the increase in photosynthesis would slow as the plants reach maturity and take up less CO2. Second, carbon stored by the plants would return to the lower atmosphere as CO2 when the plants die and decompose or burn. According to the 2007 IPCC report, plants now absorb more CO2 than they release, but by 2050 will likely release more CO2 than they take up.

Reducing the clear-cutting of rain forests in the Amazon and other tropical areas will preserve trees and other vegetation that remove some of the CO2 we add to the atmosphere. However, even if we halted all clear-cutting, climate models forecast that global warming will convert much of the Amazon’s wet forests into dry savannah during this century. This would reduce CO2 uptake by tropical forests, further accelerate global warming, and greatly decrease tropical biodiversity.


Tinkering with the Stratosphere

Explain why you agree or disagree with the proposal to inject large quantities of sulfate particles into the stratosphere every two years to help cool the troposphere


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(4) Air Pollution

Indoor Air Pollution: The Silent Killer


Indoor Air Pollution Is a Serious Problem

If you are read one book indoors, you may be inhaling more air pollutants than you would if you were outside. Indoor air pollution usually poses a much greater threat to human health than does outdoor air pollution. EPA studies have revealed some alarming facts about indoor air pollution in the United States and in other developed countries. First, levels of 11 common pollutants generally are two to five times higher inside homes and commercial buildings than they are outdoors, and as much as 100 times higher in some cases. Second, pollution levels inside cars in traffic-clogged urban areas can be as much as 18 times higher than out- side levels. Third, the health risks from exposure to such chemicals are magnified because most people in developed countries spend 70–98% of their time indoors or inside vehicles.

Since 1990, the EPA has placed indoor air pollution at the top of the list of 18 sources of cancer risk. It causes as many as 6,000 premature cancer deaths per year in the United States. At greatest risk are smokers, infants and children younger than age 5, the old, the sick, pregnant women, people with respiratory or heart problems, and factory workers.

Danish and U.S. EPA studies have linked various air pollutants found in buildings to a number of health effects, a phenomenon known as the sick-building syndrome (SBS). Such effects include dizziness, headaches, coughing, sneezing, shortness of breath, nausea, burning eyes, chronic fatigue, irritability, skin dryness and irritation, flu-like symptoms, and depression. EPA and Labor Department studies indicate that almost one in five commercial buildings in the United States is considered “sick,” exposing employees to these health risks.


GREEN CAREER: Indoor air pollution specialist According to the EPA and public health officials, the four most dangerous indoor air pollutants in developed countries are tobacco smoke; formaldehyde found in many building materials and household products; radioactive radon-222 gas; and very small particles. Formaldehyde, a colorless, extremely irritating organic chemical, is a growing problem. According to the EPA and the American Lung Association, 20–40 million Americans suffer from chronic breathing problems, dizziness, rash, headaches, sore throat, sinus and eye irritation, skin irritation, wheezing, and nausea caused by daily exposure to this chemical.

In developing countries, the indoor burning of wood, charcoal, coal, and other fuels for cooking and heating in open fires or in unvented or poorly vented stoves exposes people to dangerous levels of particulate air pollution. According to the WHO and the World Bank, indoor air pollution for the poor is by far the world’s most serious air pollution problem.

 Your Respiratory System Helps Protect You from Air Pollution

Your respiratory system helps protect you from air pollution. Hairs in your nose filter out large particles. Sticky mucus in the lining of your upper respiratory tract captures smaller (but not the smallest) particles and dissolves some gaseous pollutants. Sneezing and coughing expel contaminated air and mucus when pollutants irritate your respiratory system. In addition, hundreds of thousands of tiny mucus coated hair like structures called cilia line your upper respiratory tract. They continually wave back and forth and transport mucus and the pollutants they trap to your throat where they are swallowed or expelled. Prolonged or acute exposure to air pollutants, including tobacco smoke, can overload or break down these natural defenses. Years of smoking and breathing air pollutants can lead to lung cancer and chronic bronchitis.

Damage deeper in the lung can cause emphysema, in which irreversible damage to air sacs or alveoli leads to abnormal dilation of air spaces, loss of lung elasticity, and acute shortness of breath.

 Air Pollution Is a Big Killer

According to the WHO, at least 3 million people worldwide (most of them in Asia) die prematurely each year from the effects of air pollution—an average of 8,200 deaths per day. About 2.2 million of these deaths (73%) result from indoor air pollution, typically from heart attacks, respiratory diseases, and lung cancer related to daily breathing of polluted air. In the United States, the EPA estimates that annual deaths related to indoor and outdoor air pollution range from 150,000 to 350,000 people-equivalent to 2–3 fully loaded 200-passenger airliners crashing each day with no survivors. Millions more suffer from asthma attacks and other respiratory disorders and lose work time. Most of the deaths are related to inhalation of very small particulates from coal-burning power plants.

According to recent EPA studies, each year more than 125,000 Americans (96% of them in urban areas) get cancer from breathing soot-laden diesel fumes from buses and trucks. Other sources of these fumes include tractors, bulldozers and other construction equipment, and trains. A large diesel truck emits as much particulate matter as 150 cars, and particulate emissions from a diesel train engine equal those from 1,500 cars.

Premature deaths from air pollution in the United States, mostly from very small particles added to the atmosphere by coal-burning power plants. According to the American Lung Association, more that 2,000 scientific studies published since 1995 link particulate matter with adverse health effects.


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(3) Air Pollution

 CHINA AIRPOCOLYPSE - Air Pollution is So Bad in China, Kills 500,000 People Each Year


Several Factors Can Decrease or Increase Outdoor Air Pollution

Five natural factors help reduce outdoor air pollution. First, particles heavier than air settle out as a result of the earth’s gravity. Second, rain and snow help cleanse the air of pollutants. Third, salty sea spray from the oceans can wash out much of the particulates and other water-soluble pollutants from air that flows over the oceans from land. Fourth, winds sweep pollutants away, diluting them by mixing them with cleaner air. Fifth, some pollutants are removed by chemical reactions. For example, SO2 can react with O2 in the atmosphere to form SO3, which reacts with water vapor to form droplets of H2SO4 that fall out of the atmosphere as acid precipitation.

Six other factors can increase outdoor air pollution. First, urban buildings can slow wind speed and reduce dilution and removal of pollutants. Second, hills and mountains can reduce the flow of air in valleys below them and allow pollutant levels to build up at ground level. Third, high temperatures promote the chemical reactions leading to photochemical smog formation. Fourth, VOC emissions from certain trees and plants such as some oak species, sweet gums, poplars, and kudzu, in heavily wooded urban areas can play a large role in the formation of photochemical smog. A fifth factor-the so-called grasshopper effect-occurs when volatile air pollutants are transported from tropical and temperate areas toward the earth’s poles, especially during winter. This explains why polar bears, whales, sharks, and other top carnivores and native peoples in the Arctic have high levels of DDT and other long-lived pesticides, toxic metals (such as lead and mercury), and PCBs in their bodies, even in the absence of industrial facilities and cars.

Sixth, temperature inversions can cause pollutants to build to high levels. During daylight, the sun warms the air near the earth’s surface. Normally, this warm air and most of the pollutants it contains rise to mix and disperse the pollutants with the cooler air above it. Under certain atmospheric conditions, however, a layer of warm air can temporarily lie atop a layer of cooler air nearer the ground, creating a temperature inversion. Because the cooler air is denser than the warmer air above it, the air near the surface does not rise and mix with the air above. This allows pollutants to build up in the stagnant layer of cool air near the ground.

Two types of areas are especially susceptible to prolonged temperature inversions. The first is a town or city located in a valley surrounded by mountains where the weather turns cloudy and cold during part of the year. In such cases, the surrounding mountains and the clouds block much of the winter sunlight that causes air to heat and rise, and the mountains block the wind. As long as these stagnant conditions persist, pollutants in the valley below will build up to harmful and even lethal concentrations.

The other type of area vulnerable to temperature inversions is a city with several million motor vehicles in an area with a sunny climate, light winds, mountains on three sides, and the ocean on the other side. Here, the conditions are ideal for photochemical smog worsened by frequent thermal inversions, and the surrounding mountains prevent the polluted surface air from being blown away by sea breezes. This describes the U.S. state of California’s heavily populated Los Angeles basin, which has prolonged temperature inversions, mostly during summer and fall.

 Acid Deposition Is a Serious Regional Air Pollution Problem

Most coal-burning power plants, ore smelters, and other industrial plants in developed countries use tall smokestacks to emit sulfur dioxide, suspended particles, and nitrogen oxides high into the atmosphere where wind can mix, dilute, and disperse them.

These tall smokestacks reduce local air pollution, but can increase regional air pollution downwind. The primary pollutants (sulfur dioxide and nitrogen oxides) emitted into the atmosphere above the inversion layer may be transported as far as 1,000 kilometers (600 miles) by prevailing winds. During their trip, they form secondary pollutants such as droplets of sulfuric acid, nitric acid vapor, and particles of acid-forming sulfate and nitrate salts.

These acidic substances remain in the atmosphere for 2–14 days, depending mostly on prevailing winds, precipitation, and other weather patterns. During this period they descend to the earth’s surface in two forms: wet deposition consisting of acidic rain, snow, fog, and cloud vapor and dry deposition consisting of acidic particles.

The resulting mixture is called acid deposition - sometimes termed acid rain-with a pH. Most dry deposition occurs within 2-3 days fairly near the emission sources, whereas most wet deposition takes place within 4-14 days in more distant downwind areas.

Acid deposition has been occurring since the industrial revolution. In 1872, British chemist Robert A. Smith coined the term acid rain after observing that rain was eating away stone in the walls of buildings in major industrial areas. Acid deposition occurs when human activities disrupt the natural nitrogen cycle, by adding large amounts of nitrogen oxides to the atmosphere, and disrupt the sulfur cycle by adding excessive amounts of sulfur dioxide to the atmosphere.

Acid deposition is a regional air pollution problem in areas that lie downwind from coalburning facilities and from urban areas with large numbers of cars. Such areas include the eastern United States and other parts of the world. Older coal-burning power and industrial plants without adequate pollution controls in the Midwestern United States emit the largest quantities of sulfur dioxide and other pollutants that can cause acid deposition. Because of these emissions, and those of other urban industries and motor vehicles, typical precipitation in the eastern United States is at least 10 times more acidic than natural precipitation. Some mountaintop forests in the eastern United States and east of Los Angeles, California, are bathed in fog and dews as acidic as lemon juice-about 1,000 times the acidity of normal precipitation. In some areas, soils contain basic compounds such as calcium carbonate (CaCO3) or limestone that can react with and neutralize, or buffer, some inputs of acids.

The areas most sensitive to acid deposition are those with thin, acidic soils that provide no such natural buffering and those where the buffering capacity of soils has been depleted by decades of acid deposition. Many acid-producing chemicals generated in one country are exported to other countries by prevailing winds. For example, acidic emissions from the United Kingdom and Germany blow into Norway and neighboring countries. The worst acid deposition occurs in Asia, especially China, which gets 69% of its total energy and 75% of its electricity from burning coal. In addition, air pollution that contributes to acid deposition and enhanced global warming is produced by the greatly increased use of cheap diesel generators to provide electricity for rural villages and power for irrigation pumps in China, India, and other developing countries.

 Acid Deposition Has a Number of Harmful Effects

 Acid deposition causes harm in several ways. It contributes to human respiratory diseases, and can leach toxic metals (such as lead and mercury) from soils and rocks into acidic lakes used as sources of drinking water. These toxic metals can accumulate in the tissues of fish eaten by people, other mammals, and birds. Currently 45 U.S. states have issued warnings to people (especially pregnant women) to avoid eating fish caught from some of their waters because of mercury contamination. Acid deposition also damages statues, national monuments, buildings, metals, and car finishes, and acidic particles in the air decrease visibility. Because of excess acidity, several thousand lakes in Norway and Sweden contain no fish, and many more lakes there have lost most of their acid-neutralizing capacity.

In Ontario, Canada, at least 1,200 acidified lakes contain few if any fish, and some fish populations in thousands of other lakes are declining because of increased acidity. In the United States, several hundred lakes (most in the Northeast) are threatened in this way. But some lakes are acidic because they are surrounded by naturally acidic soils.

Acid deposition (often along with other air pollutants such as ozone) can harm forests and crops by leaching essential plant nutrients such as calcium and magnesium from soils and releasing ions of aluminum, lead, cadmium, and mercury, which are toxic to the trees. This reduces plant productivity, tree growth, and the ability of soils to buffer acidic inputs. Acid deposition rarely kills trees directly, but can weaken them and leave them vulnerable to stresses such as severe cold, diseases, insect attacks, and drought. Mountaintop forests are the terrestrial areas hardest hit by acid deposition. These areas tend to have thin soils without much buffering capacity. And trees on mountaintops (especially conifers like red spruce and balsam fir) are bathed almost continuously in highly acidic fog and clouds. Most of the world’s forests and lakes are not being destroyed or seriously harmed by acid deposition. Rather, this regional problem is harming forests and lakes that lie downwind from coal-burning facilities and from large car-dominated cities without adequate pollution controls.

 We Know How to Reduce Acid

Deposition summarizes ways to reduce acid deposition. According to most scientists studying the problem, the best solutions are prevention approaches that reduce or eliminate emissions of sulfur dioxide, nitrogen oxides, and particulates. Controlling acid deposition is politically difficult. One problem is that the people and ecosystems it affects often are quite distant from those that cause the problem. Also, countries with large supplies of coal (such as China, India, Russia, and the United States) have a strong incentive to use it as a major energy resource. Owners of coal-burning power plants say that adding the latest pollution control equipment, using low-sulfur coal, or removing sulfur from coal would increase the cost of electricity for consumers. Environmental scientists counter that affordable and much cleaner resources are available to produce electricity. They also point out that the largely hidden health and environmental costs of burning coal are up to five times its market price. Including these costs in market prices would reduce coal use, spur the use of cleaner ways to burn coal, and help prevent acid deposition. Air pollution laws in the United States have reduced the acidity of rainfall in parts of the Northeast, Mid-Atlantic, and Midwest regions, but there is still a long way to go in reducing emissions from older coal burning power and industrial plants. Some plants have lowered SO2 emissions by switching from high-sulfur to low-sulfur coals. However, this has increased CO2 emissions that contribute to global warming, because low-sulfur coal has a lower heat value, which means that more coal must be burned to generate a given amount of electricity. Low-sulfur coal also has higher levels of toxic mercury and other trace metals, so burning it emits more of these hazardous chemicals into the atmosphere. Everything is connected.


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(2) Pollution

Air Pollution Causes More than 6 Million Deaths Worldwide


Less forgiving than our planet

A facility known as Biosphere 2 was designed to test a supposition often made by economists - which technology can substitute for natural life support systems. Biosphere 2 was to model a spacecraft that could allow humans to travel in space indefinitely. Within the structure, everything was to be sustainable. Built in the State of Arizona at a cost of $200 million, the 3.2 acres (1.3 hectares) of Biosphere 2 are a closed-off mini-Earth containing tiny biomes – a marsh from the Florida Everglades, an equatorial rain forest, a coastal desert, a savanna with a stream and grasses from three continents, an artificial mini-ocean with a coral reef, plus an orchard and intensive agricultural area. Its underbelly holds a maze of plumbing, generators, and tanks. In 1991, eight people started living in Biosphere 2 to test its ability to support life. They lived within the facility for two years. The first year went well, but in the second, crops failed, and people grew thin. They became dizzy as atmospheric oxygen levels fell from 21% to 14% – a level typical of a 14 000 feet (4270 m) elevation. This occurred because excessive organic matter in the soil absorbed oxygen from the air as did the type of concrete used. Atmospheric carbon dioxide “spiked erratically,” while nitrous oxide rose to levels hazardous to brain function. Vines and algal mats overgrew other vegetation. Water became polluted.

The Biosphere initially had 3800 plant and animal species. Among the 25 introduced vertebrate species 19 died out over the two years, and only a few birds survived. All the Biosphere’s pollinators – essential to sustainable plant communities – became extinct. Excitable “crazy” ants destroyed most other insects.

▪In 1997, Columbia University took over Biosphere 2 for use as an educational facility designed to teach Earth stewardship, a place to “build planetary managers of the future.” Its research efforts included studying the effects of various levels of the greenhouse gas carbon dioxide on plant communities. That effort ended and the University of Arizona is now in charge.

▪ Someone noted that Biosphere 2 is less forgiving than our planet.

But Earth is a closed system too. History records many examples of civilizations that failed or grew weak after severely impacting their local environments. But survivors often moved on to other environments. Today, many people still struggle to “move on,” but there are fewer and fewer fresh locales into which Earth’s huge population can move.

The technical problems of Biosphere 2 could probably be solved. But for the whole Earth, or major parts of it, can we substitute technology for nature’s services, for breathable air, or for fertile clean soil?

What is happening to Earth’s ecosystems?

Keeping in mind our absolute dependence on Earth’s ecosystems and the major stresses on them, how well are they still providing their natural goods and services? The first systematic examination of this question was a four-year $20 million study, the Millennium Ecosystem Assessment (MEA). Carried out by 1400 scientists worldwide under the aegis of the UN Environment Program’s (UNEP), the MEA evaluated the health of the planet’s forests,

coastlines, inland waters, shrub lands, dry lands, deserts, agricultural lands, and other ecosystems vital to human and natural welfare. Helping investigators to envision what was happening were 16 000 photographs donated by the US National Aeronautics and Space Administration (NASA). Taken from space by satellite, these showed changes occurring in the 1990s in biomes such as coastlines, mountains, and agricultural land.

In 2005 MEA provided some answers as to what is happening to ecosystem services. Their report revealed that at least 60% of services supporting life on Earth including fresh water, fisheries, and many other services are being used unsustainably. The report, Living Beyond Our Means: Natural Assets and HumanWell-being,13 has shown that we are using about 1.25 Earths’ worth of resources, even while human population and consumption continues to increase. Consequences of environmental degradation could become more obvious in coming years. Although results were extremely worrisome, the study pointed toward means by which we can improve ecosystem management.

See http://millenniumassessment.org/en/index.aspx, home page of the MEA, which links to the reports summary and other reports including Living Beyond Our Means. Also see the World Resources Institutes EarthTrends at http://earthtrends.wri.org/ for more useful information on Earths ecosystems.

When pollution is obvious

If you read that a pollutant is “any substance introduced into the environment that adversely affects the usefulness of a resource” you may yawn. But pollution literally hits you if you live in a city where emissions from cars, trucks, and motorbikes sting your eyes, congest your nose, cause your head to ache, or tighten your breathing.

▪ In the 1960s and ’70s, pollution in the United States, a wealthy country, was often blatant. Some rivers were obviously polluted by industries operating on their banks. Oil floating on the surface of Ohio’s Cuyahoga River caught on fire more than once. One fire in 1959 burned for 8 days.

▪ Air pollution was obvious too. In industrial cities soot drifted onto streets and clothing, and into homes. Severe air pollution episodes increased hospital admissions killing sensitive people. Trash burned in open dumps.

▪ Heavy pesticide use killed fish, birds, and other animals.

▪ The new century finds the environment in industrialized countries improved. But continuing population growth in the United States and unremitting, indeed accelerated, land development may be reversing some of that progress. And the United States, once an environmental leader, abandoned that role in the first decade of the twenty-first century.

Just as a weed is “a plant out of place,” a pollutant is “a chemical out of place.” Oil enclosed within a tanker is not a pollutant. Spilled into the environment, it is. However, doing harm often involves more than being out of place. A small oil spill may go unnoticed, but a large one can be disastrous. Circumstances are important too. If the oil is of a type easily degraded, or one that evaporates easily, or if wind blows the spill quickly away from a shoreline, there may be little harm. But, coming ashore, oil may devastate animals, birds, and other shore-dwelling organisms.

Almost any substance, synthetic or natural, can pollute. However, it is synthetic and other industrial chemicals that are emphasized here. If we learn that industrial chemicals in a water body are obviously impairing the ability of birds to reproduce, or are associated with fish tumors we all agree that the water is polluted. But what if only tiny amounts of industrial chemicals are present and living creatures are apparently unaffected? Is the water polluted?

Some would say “yes,” arguing that chronic effects could result, i.e., adverse effects resulting from long-term exposure to even very low concentrations of a substance.

 ▪ The word waste differs from pollutant, although a waste can be a pollutant too. Waste refers to material such as garbage, trash, construction debris: materials that have reached the end of their useful life.

▪ See bellow a description of how pollutant concentrations are described.

Pollution is often less obvious if you live in a wealthy country where the twentieth century brought cleaner air and drinking water, sewage treatment, safe food laws, and food refrigeration. But it took many years and many billions of dollars to reach those results. And wealth does not guarantee an unspoiled environment. For example, parts of the American Appalachian Mountains suffer destruction and pollution resulting from mountaintop removal mining. Or think about wealthy Hong Kong. In the 1990s, the beaches of this island were too polluted for swimming. High concentrations of hazardous industrial metals, livestock waste, and human waste polluted its rivers, and large amounts of trash polluted the harbor. However, between 1993 and 2000, hazardous metal discharges were reduced from 15 432 lb/day (7000 kg/day) to 4409 lb/day (2000 kg/day). And, Hong Kong increasingly collects and treats sewage before releasing it into the harbor. However, air pollution remains critical. In the mid-1990s, exhausts from motor vehicles resulted in 25% of the population suffering from respiratory problems. Today, despite better air pollution controls, heavy smog often blankets Hong Kong. Up to half of this enters Hong Kong from nearby Chinese cities in Guangdong Province. But part of the imported pollution comes from facilities owned by Hong Kong companies - operating on the mainland with poor pollution controls.

Terms used to describe pollutant concentration

ppm = parts per milliona

ppb = parts per billion (one thousand times smaller than ppm)

ppt = parts per trillion (1 million times smaller than ppm)

ppq = parts per quadrillion (1 billion times smaller than ppm)

To grasp these concentrations, consider the following:

1 ppm = 1 pound contaminant in 500 tons (1 million pounds)

1 ppb = 1 pound of contaminant in 500 000 tons

1 ppt = 1 pound of contaminant in 500 000 000 tons

1 ppq = 1 pound of contaminant in 500 000 000 000 tons.

For a different perspective, think about periods of time:

1 ppm is equivalent to 1 second in 11.6 days

1 ppb is equivalent to 1 second in 32 years

1 ppt is equivalent to 1 second in 32 000 years

1 ppq is equivalent to 1 second in 32 000 000 years.

a ppm, ppb, etc. refer to parts by weight in soil, water, or food. In air, they refer to parts per volume.

 Why does pollution happen?

Unless you assume that people and industry deliberately pollute, why does pollution occur? It happens because no process is 100% efficient. Consider your own body - it cannot use 100% of the food you eat.

▪ The gastrointestinal (GI) tract does not break down the fiber in the food you eat, and this is excreted from the body as solid waste.

▪ Enzymes in the gut do break down other foods into molecules that can cross the GI wall into the bloodstream, which carries the nutrition throughout your body. But the body cannot use 100% of the nutrient value, and a portion is excreted into urine as water-soluble waste.

▪ Also, your body cannot convert all the potential energy in food into useful energy- part becomes waste energy.

As with your body, no other process, natural or human, such as manufacturing or fuel burning, is 100% efficient: each produces pollution and waste, and waste energy. Lack of prevention, carelessness, unwillingness to invest in good technology, or lack of appropriate technology aggravates the waste and pollution produced. Architect William McDonough and chemist Michael Braungart observe, “Pollution is a symbol of design failure.” In other words, wastes need not be wastes and pollutants need not be pollutants. We should be able to return these to the manufacturing process, or else make sure the wastes involved are able to biodegrade harmlessly in the environment. 

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