Air pollution sources, effects, and control measures

Air Pollution: A Testament to Human History

Air pollution is woven throughout the fabric of our modern life. A by-product of the manner in which we build our cities, air pollution is waste remaining from the ways we produce our goods, transport ourselves and our goods, and generate the energy to heat and light the places we live, play, and work.." (Davis, 1)

The most important natural resource on which humans depend is often overlooked. It is around us and inside of us; this vital resource is everywhere. It is vital to our survival, yet although it is almost omnipresent on earth, the supply is in danger. The air we breathe supplies us and all animals with oxygen, an essential element for the body to live. Air as we know it is almost completely composed of nitrogen, oxygen, water vapor, and inert gases. Unfortunately, the composition of air has been affected by the humans that have released substances into the air that would not naturally occur, some of which can be harmful in any number of ways to the planet and to humans as individuals. This tainting of the earth's atmosphere is known commonly as air pollution. "It is not easy to define pollution. A dictionary defines it as 'the contamination of one substance by another so that the former is unfit for its intended use.' Substances that are useful or even essential in certain places at certain quantities can become pollutants if they occur in too large a quantity in the wrong place." (Becklane)

Common types of pollution and associated problems that may come to mind when the subject is broached include smog, acid rain, the greenhouse effect, and depletion of the ozone layer. However, air pollution is a far more complex problem than most people realize; air pollution affects both the indoors and the outdoors, and has a history as old as the world.

People have suffered from health problems caused by air pollution for centuries, and although the causes of the symptoms remained unknown for some time, the pollution was just as harmful. The coal-smoke filled streets of London during the Industrial Revolution and the less visible pollution we know today have a great deal in common. Air pollution is also interconnected to other forms of pollution such as land and water contamination, and it is a problem that must be understood and addressed on an international level from many angles.

Natural Cycles and Natural Pollution

It is commonly believed that humans and unnatural human products and processes are the sole cause of air pollution. Although human-created air pollution has existed throughout human history, it is actually speculated that up until only a few hundred years ago, air pollutants on a worldwide scale occurred mainly from natural sources. "Such natural processes as forest fires, decaying vegetation, dust storms, and volcanic eruptions have always contaminated the air." (Davis, 2) Natural air pollution occurs from sources such as volcanoes, forest fires (which are actually caused by humans some of the time), sea salt from the ocean, dust from space, pollen from trees and plants, swamps and wetlands, decaying vegetation, and dust storms. It is believed by some experts that some form of natural pollution, such as a volcanic eruption or meteor falling from space, was actually the cause of the extinction of dinosaurs. Some of the same pollutants that are of a great concern regarding air pollution that is caused by humans are released by these natural sources. For example, volcanoes release sulfur oxides and harmful paticulates; forest fires release carbon monoxide and dioxide, nitrogen oxides, and particulates; and decaying plants release methane and hydrogen sulfide. Of these sources, volcanoes are perhaps one of the most obvious and destructive is the volcano. "As recently as 1991, Mount Pinatubo in the Philippines erupted, killing 200 people and emitting particulates and climatic influences." (Davis, 2)

In a recent volcanic incident in Hawaii, people living downwind of the volcano reported reduced visibility, health complaints, and even damage to crops. The volcanic smog, or "vog" as it is colloquially known, is created when SO2 and the other volcanic gasses combine and interact with the atmosphere -- the oxygen, water vapor, dust particles, and even the sunlight are contributing factors to the vog. The vog, like the smog known to big cities, is a visible haze of gasses and particles, and in this vog can be found large amounts of sulfuric acid. Other toxic metals can be found in trace amounts, including selenium, mercury, arsenic, and iridium, and the effects of vog can spread for long distances away from the volcano itself.

Why is human pollution such an issue to environmentalists, then, if nature itself creates such pollution? One reason is that today, "natural events like these only cause about ten percent of air pollution -- the rest is caused by human activities." (Baines, 8) Natural pollution, if it were not for the pollution caused by humans, would not be a significant concern because it is part of the natural cycle of the world. In the natural cycle, "nothing is wasted and nature produces relatively little pollution. The gases we use from the air are recycled. Animals breathe in oxygen and release carbon dioxide, while plants use up carbon dioxide and release oxygen during photosynthesis. So the gases in the air remain essentially in balance when left to nature. Human activity has disturbed these natural cycles." (Becklane, 5) The total production of the gasses and paticulates that are recognized as pollutants may actually be greater from natural sources than from human-created sources, however the atmosphere is able to disperse and lower these releases and recycle them into a form that is not harmful.

Anthropogenic Air Pollution

Obviously, nature is not the only cause of air pollution. Anthropogenic air pollution is that caused by humans. While natural air pollution has theoretically been around since the beginning of time, anthropogenic air pollution has been around since the beginning of modern man. "One of the reasons the tribes of early history were nomadic was to move periodically away from the stench of the animal, vegetable, and human wastes they generated. When the tribesmen learned to use fire, they used it for millennia in a way that filled the air inside their living quarters with the products of incomplete combustion." (Boubel, 3)

It is a general assumption that air pollution is a post-1900 or even a post- World War II phenomenon, but it is a problem dating back to ancient times. The waste and pollution caused by humans would only increase as they became more developed and more advanced. Records dating as far back as 900 BC have been found complaining of air pollution. King Tukulti, an Egyptian Pharaoh, left records regarding the terrible smell in the air in the town of Hit, located west of Babylon, where the ulmeta rocks of the asphalt mines emitted a terrible odor. Today we know that these rocks are high in sulfur dioxide and hydrogen sulfide. In AD 61, Seneca, the Roman philosopher, would report that the chimneys of Rome released heavy vapors and soot that made it difficult to breathe. In fact, lung tissue samples from both frozen and mummified remains of ancient humans shows anthracosis, or blackening of the lungs, which is the same condition that would be so common in the smoky industrial centers of the late nineteenth and early twentieth centuries. "The principal industries associated with the production of air pollution in the centuries preceding the Industrial Revolution were metallurgy, ceramics, and preservation of animal products. In the bronze and iron ages, villages were exposed to dust and fumes from many sources." (Boubel, 4)

Ancient times would experience many of the same problems as the recent eras. Where people congregated in large numbers, fuels would be burned for both domestic and commercial purposes, and smoke problems would gradually develop in these centers. As the human population grew, human activity and use of pollution-causing products and processes would also increase, and pollution would eventually be brought to a serious level. Unfortunately, by the time pollution would become such a serious problem that it was noticed largely by the general public and would be cause for widespread protest, it would be built into the social and economic fabric of the communities it effected, and other hardships would have to be endured in order to eradicate the causes of pollution. Instead, the wealthy would move away from the polluted centers into less populated areas with cleaner air. This is the same pattern we see today and throughout history in urban centers, where the wealthy move further and further away from the center of the city, leaving the poor in the most polluted areas.

The Pollution Revolution

The Industrial Revolution would bring a new age in anthropogenic air pollution. "The Industrial Revolution was the consequence of the harnessing of steam to provide power to pump water and move machinery," (Boubel, 4) and the steam engines and steam turbines which were capable of this required steam boilers, which were fired by either vegetable or fossil fuels, both of which are significant causes of air pollution. London is a perfect example of the development of urban air pollution. Beginning in the 1200s, a certain type of coal called "sea coal" was shipped to London. Although it was met with distaste for the smoke, soot, and smell from using it, by the mid-1600s almost everyone in London, including the industry, the wealthy, and the poor, used this soft bituminous coal as the main source of fuel. It was, after all, far more abundant and less expensive than fire wood. However, this coal was met with protest from many sources before it would reach that level of acceptance.

One of the reasons coal was met with protest was because of a lingering belief in an ancient Greek concept which would be called miasmas throughout the Medieval era. It was believed that foul smells, such as swamp vapors and coal fumes, were dangerous, unhealthy, and a carrier of disease. While the reasoning behind this medical belief that would linger through the nineteenth century were not completely correct, it was true that the polluted air from these sources was in fact harmful. The mines north of London were so pungent that "in 1257, Queen Elanor, wife of Henry III, was so sickened by the stench of coal smoke at Nottingham Castle that she fled to preserve her health." (Dewey, 17) Perhaps it was the royal distaste for the stench that brought about some attempts to address public concern over the smoke. "By the end of the thirteenth century, the growing smoke problem in London brought perhaps the earliest air pollution control effort in the Western world. Following public complaints, in 1285 a commission was created in London to investigate the problems resulting from coal use, followed by a 1306 royal proclamation banning the use of sea coal, allegedly under pain of death -- a regulation that was largely ignored and left unenforced, like many that followed." (Dewey, 17) The city of London attempted various control methods, including higher chimneys, limits on when furnaces and coal could be used, zoning to keep certain factories away from fruit trees, and even taxing and regulation of coal shipments. All of these methods -- like most pollution patterns -- would be repeated in the twentieth century with little or no noticeable change. The research and control efforts of the seventeenth century would also be strikingly similar to those used in the nineteenth and twentieth centuries, and included charring coal, and combining coal with over substances to make it less noxious or acidic. Even then, air pollution studies linked coal smoke and elevated death rates, but most proposed efforts to help the situation were defeated by economic interest and public apathy.

By the end of the 18th century, more than a million tons of coal would be burned each year, and London had earned the nickname "The Big Smoke."

The predominant air pollution problem of the nineteenth century was smoke and ash from the burning of coal or oil in the boiler furnaces of stationary power plants, locomotives, and marine vessels, and in home heating fireplaces and furnaces." (Boubel, 5) Londoners wore drab or black clothing because soot was everywhere and it was impossible to keep clothing clean. Even indoors, paintings, books, maps, and documents were eaten away by the corrosive coal smoke. Outside, iron, brick, and marble were corroded by the smoke, and many types of plants were wiped out of London's parks. It was in the 19th century that it would be fully understood that not all coal was the same. Some regulations were passed that forced some London businesses to burn the somewhat cleaner anthracite coal instead of the traditional sea coal, but due to expense most businesses would continue to use the traditional coal. This problem would later be repeated in Pittsburgh and St. Louis; "This limited tinkering with fuel substitution in the absence of sufficient political will to make it widespread and permanent would be another recurring theme in other industrializing nations." (Dewey, 18)

In the United States, no "smoke abatement" (or air pollution control) efforts had been put into effect until the 1880s, and even then it was considered a municipal responsibility with no interference from the federal or state governments. these first efforts were directed at industrial, locomotive, and marine uses of fuel, ignoring the problems of domestic fuel use. "As the nineteenth century drew to a close, the pollution of the air of mill towns the world over had risen to a peak; damage to vegetation from the smelting of sulfide ores was recognized as a problem everywhere it was practiced." (Boubel, 7) In the 19th century, some technological developments that would change air pollution patterns included the stoker for mechanical firing of coal, the scrubber for removing acid gases from gas streams, house dust collectors, and many new physical and chemical principles added to the design processes of fuels and industry. Still, even through 1925, there would be no significant changes in legislation regarding air pollution, even as the cities and factories grew, increasing the problems. As the steam engine was replaced by the electric motor, the air pollution source moved from the factory to the electric generating station, but the problem remained.