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What is Air Pollution?

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Sunlight pierces the smog over the Beijing skyline.

Air pollution poses a serious threat to public health.

Andrew Wong/Getty Images
Question: What is Air Pollution?

What is air pollution? That may seem like a question that doesn't really need to be asked. Surely, everyone already knows the answer. Air pollution is, well, wait now . . . OK, what is air pollution, exactly?

Answer: Ask most people "what is air pollution?" and they will answer "smog" (another word for ground-level ozone), the smelly stuff that turns the air brown or grey and hovers over urban centers like Los Angeles, Mexico City and Beijing. But air pollution comes in many forms, and may include a number of different pollutants and toxins in various combinations.

What Constitutes Air Pollution?
The two most widespread types of air pollution are the aforementioned ozone (smog) and particle pollution (soot), but air pollution also may include serious pollutants such as carbon monoxide, lead, nitrogen dioxide and sulfur dioxide, and toxins such as mercury, arsenic, benzene, formaldehyde and acid gases.

The specific composition of air pollution in a particular location depends primarily on the source, or sources, of the pollution. Automobile exhaust, coal-fired power plants, industrial factories and other pollution sources all spew different types of pollutants and toxins into the air.

Air Pollution and Your Health
Air pollution hovers at unhealthy levels in almost every major U.S. city, interfering with people’s ability to breathe, causing or aggravating many serious health conditions, and placing lives at risk. Many cities worldwide face the same issues, even in emerging economies such as China and India.

Breathing either ozone or particle pollution, or other types of air pollution, can seriously damage your health. Inhaling ozone (smog) can irritate your lungs, "resulting in something like a bad sunburn within the lungs," according to the American Lung Association. Breathing particle pollution (soot) can increase your risk of heart attack, stroke and early death, and necessitate emergency-room visits for people with asthma, diabetes and cardiovascular disease.

Air pollution is also a problem in developing countries. More than half the world's population still cook their meals with wood, dung, coal or other solid fuels over open fires or on primitive stoves inside their homes, breathing high levels of pollutants such as particulate pollution and carbon monoxide, which results in 1.5 million unnecessary deaths every year.

Who is Most at Risk from Air Pollution?
The health risks of air pollution are greatest among infants and young children, older adults, and people with respiratory diseases such as asthma.

People who work or exercise outside also face increased health risks from the effects of air pollution, along with people who live or work near busy highways, factories or power plants. In addition, minorities and people with low incomes are often disproportionately affected by air pollution because of where they live, which places them at higher risk for illnesses related to air pollution.

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