The Science of Sustainability

Pollution is the contamination, harm, or disruption of the natural environment through the emissions of harmful substances. Pollution is most typically associated with anthropogenic sources but can also occur from natural activity, such as volcanic eruptions. Pollution can impact air, water, and land. Pollutants include domestic, industrial, and agricultural waste. It comes in many different forms and can be chemical substances or noise, heat, or light.

Pollution can be either point source or nonpoint source. Point source is a specific and easily identifiable source of pollution, such as a factory or power plant. Nonpoint sources consist of many small, distributed sources of a pollutant that are difficult to individually identify and on their own may not be that harmful but in aggregate are significant sources of pollution. A classic example of nonpoint source would be soap detergents, fertilizers, and other commonly used chemicals and products from many residences and businesses that then contaminate watersheds with high levels of nitrogen. Nonpoint sources tend to be more complex to regulate for pollution emissions.

Pollution is not just toxic substances; it can be pollutants that are actually part of a healthful ecosystem in the proper quantities, such as nitrogen or carbon dioxide, but that in excessive quantities alter the normal functioning of an ecosystem resulting in harm to the ecosystem. Pollution can range from highly dangerous radioactive materials to airborne dust (a substance that is typically benign) resulting from land erosion.

Air pollution, the contamination of the atmosphere by airborne pollutants, is most often related to combustion of fuel from either stationary or mobile sources. Stationary sources include the smoke stacks of factories, power plants, and furnaces or boilers. Mobile sources refer to motor vehicles, aircraft, and other forms of fossil-fuel-based transportation. Paints, chemicals, and aerosol sprays also can pollute the air. Natural sources of air pollution include dust, methane from livestock, volcanic activity, wildfires, and even vegetation.

Concerns over air pollution are not just a modern occurrence but date back many centuries. In 1272, King Edward I banned the burning of sea-coal in England after the smoke was having deleterious effects on the city of London. In fact, the punishment was pretty steep - death by hanging. And it was a punishment that was enforced. Nowadays, fines are a more typical punishment for any type of pollution.

In the United States, California has led the nation in regulating the emissions of air pollution, primarily because it was one of the first states in the nation to locally observe the detrimental impacts of air pollution. Los Angeles has been the focus point for air pollution in California with severe bouts of smog for at least the past one hundred years. The first "officially" recognized episode of smog occurred in Los Angeles during the summer of 1943. Visibility was reduced to three blocks and people suffered from stinging eyes, difficulty breathing, nausea, and vomiting.

Growing concern over the harmful environmental impacts of industry motivated the US environmental movement in the 1960s and 1970s. The movement resulted in the passage of many major environmental laws that impact the business climate of the United States today. See the chapter on government, public policy, and sustainable business for a more detailed discussion.

Pollution continues to be a major focus globally. China, which has become increasingly industrialized, now finds that half of its water can no longer be used for human consumption, and over a quarter is so toxic that it is unsafe even for industrial use.