Here is your short article on Air Pollution

Because of air’s mobility, it has a high natural capability for reducing the impact of air pollution on ecosystems. However, when winds are clam in areas of high population density, air pollution can be extremely serious and even life-threatening.

For example, during one brief period in 1952, smoke density and sulfur dioxide (S0₂) concentrations in London rose above normal, and death rates soared from about 250 per day to a peak of nearly 1,000. In 6 days, 4,000 more people had died than was normal for the period, and during the next 2 months, 8,000 more people than usual died.

Most people can tolerate some air pollution for extended periods of time. However, long-term exposure to air pollutants has many adverse effects on health.

The largest volume and the most serious air pollutants, many of which are carcinogenic, are emissions from the burning of fossil fuels. Moreover, when various hydrocarbons and nitrogen oxides from automobile emissions combine under the action of sunlight, they form ozone (0₃) and the other health-threatening constituents of the atmospheric haze known as photochemical smog.

One of the areas most notorious for smog episodes is Los Angeles, California, whose many automobiles and abundant sunshine produce substantial amounts of smog.

The problem is serious because of the city’s frequent temperature inversions, which result when a cool, humid breeze flows in under a stationary high-pressure layer of warm, dry air (ordinarily air temperature decreases with altitude). Pollutants generated at ground level become trapped under the impenetrable layer of warm air.

The mountains that form a broad semicircle to the norht of the Los Angeles area enhance the polluting effect by occasionally trapping the inversion in the basin for many days at a time, with air quality worsening daily.

Temperature inversions and health-threatening air quality crises also occur in the midwestem United States whenever high (high-pressure weather systems) stall for several days during warm weather. A major episode occurred in August 1969 that affected several large cities for up to 10 days.

The crisis is listed as episode 104 in United States Weather Bureau records because it was the one hundred and fourth high-air-potential (HAPP) episode that covered more than 194,000 km² pollution (75,000 square miles) and lasted more than 36 hours since monitoring began in the early 1960s. HAPP episodes covering less area are not numbered; they occur more than 25 percent of the time over almost all of the United States.

Long-Term Effect of Moderate Air Pollution on Health. Long-term, moderate air pollution actually causes more disease and death than do acute crises. Long-term exposure to air pollutants increases the risks of contracting cancer and of developing respiratory diseases such as emphysema.

Although precise data about the long-term effects on health of each of the various pollutants are difficult to obtain, it is well agreed that air pollution is harmful to health. One somewhat useful approach to studying its effects has been to compare mortality (deaths) and morbidity (serious illness) data for a given city with the concentrations of various pollutant found in its air.

For example, there is a high correlation between the concentration of heavy industries and the number of deaths due to cancer. World Health Organization data indicate that 80 to 90 percent of all human cancers are environmentally related or induced. Certain types of cancers occur in greatest frequency near factories producing certain products, for example, liver cancer incidence is high near synthetic rubber factories. Air pollution is the suspected cause.

Our understanding of the injurious effects of long-term exposure to some of the airborne pollutants in cities has been enhanced by studies of cigarette smokers. Cigarette smoke contains many of the same pollutants found in air of large cities, for example, carbon dioxide (CO₂), carbon monoxide (CO), and at least seven polycyclic (multiple ring) hydrocarbons that can produce cancer in animals under certain conditions.

Numerous studies have confirmed that the incidence of lung cancer, emphysema, and coronary artery disease is far greater in smokers, whether they live in rural cities or in environments, and is in direct proportion to the number of cigarettes they smoke per day and the number of years they have smoked.

Acid Rain. An increasingly serious problem has lately resulted from fossil fuel combustion products, the most troublesome of which are nitrogen oxide (NO and NO₂), hydrogen sulphide (H₂S), and sulphur dioxide (SO₂). Dissolved in atmospheric moisture, these compounds produce nitric acid (HNO₂) and sulphuric acid (H₂S0₄), both strong mineral acids. The resulting acid rain has destructive effects on freshwater and soil ecosystems, including ones thousands of miles from the pollution source.

The Control of Air Pollution. There are two basic, practicable approaches to controlling the quality of the air we breathe. One is to limit the pollutants emitted into the air, for example, by the burning of sulphur-free oil and coal, orgy using sophisticated, expensive technology that is still being developed. The other approach is to choose alternative technologies or sources of energy. Wind, water, and solar power, for example, are far less polluting than is the burning of any fossil fuels.

Likewise, the use of bicycles and battery-powered cars is far less polluting than the use of vehicles powered by internal combustion engines.