Air pollution

Air pollution is a broad term applied to any chemical, physical (particulate matter), or biological agent that modifies the natural characteristics of the atmosphere.

The atmosphere is a complex, dynamic natural gaseous system that is essential to support life on planet earth.

Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the earth's ecosystems. Worldwide air pollution is responsible for large numbers of deaths and cases of respiratory disease.

Enforced air quality standards, like the Clean Air Act in the United States, have reduced the presence of some pollutants.

While major stationary sources are often identified with air pollution, the greatest source of emissions are actually mobile sources, principally the automobile.

There are many available air pollution control technologies and urban planning strategies available to reduce air pollution; however, worldwide costs of addressing the issue are high.

The most immediate method of improving air quality would be the use of bioethanol fuel, biodiesel, solar energy, and hybrid vehicle technologies.

The World Health Organization estimates that 4.6 million people die each year from causes directly attributable to air pollution.

Many of these mortalities are attributable to indoor air pollution.

Worldwide more deaths per year are linked to air pollution than to automobile accidents.

Research published in 2005 suggests that 310,000 Europeans die from air pollution annually.

Direct causes of air pollution related deaths include aggravated asthma, bronchitis, emphysema, lung and heart diseases, and respiratory allergies

Smog

Smog is a kind of air pollution, originally named for the mixture of smoke and fog in the air.

Classic smog results from large amounts of coal burning in an area and is caused by a mixture of smoke and sulfur dioxide.

In the 1950s a new type of smog, known as Photochemical Smog, was first described.

Smog is a problem in a number of cities and continues to harm human health.

Ground-level ozone, sulfur dioxide, nitrogen dioxide carbon monoxide are especially harmful for senior citizens, children, and people with heart and lung conditions such as emphysema, bronchitis, and asthma.

It can inflame breathing passages, decreasing the lungs' working capacity, and causing shortness of breath, pain when inhaling deeply, wheezing, and coughing.

It can cause eye and nose irritation and it dries out the protective membranes of the nose and throat and interferes with the body's ability to fight infection, increasing susceptibility to illness.

Hospital admissions and respiratory deaths often increase during periods when ozone levels are high.

EPA has developed an Air Quality index to help explain air pollution levels to the general public.

8 hour average ozone concentrations of 85 to 104 ppbv are described as "Unhealthy for Sensitive Groups", 105 ppbv to 124 ppbv as "unhealthy" and 125 ppb to 404 ppb as "very unhealthy." Smog can form in almost any climate where industries or cities release large amounts of air pollution.

However, it is worse during periods of warmer, sunnier weather when the upper air is warm enough to inhibit vertical circulation.

It is especially prevalent in geologic basins encircled by hills or mountains.

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