The underappreciated effects of air pollution

Three major studies this week underscored the dangers of air pollution, even at what the government deems safe levels.

The studies – here, here and here – show higher levels of air pollution are associated with greater risks of stroke, heart attacks and cognitive decline.

Air pollution is a deeply underappreciated risk to health. More than half of the U.S. population lives in areas where either the ozone or particle pollution – or both – are often dangerous to breathe.

Ozone is the primary ingredient of smog. Unlike the beneficial ozone layer in the upper atmosphere that shields the sun’s ultraviolet radiation, ground-level ozone attacks lung tissue by reacting chemically with it. Ozone is formed when nitrogen oxides (NOx) and volatile organic compounds (VOCs) come in contact with heat and sunlight. NOx are emitted by power plans, motor vehicles and other sources of high-heat combustion. VOCs sources include motor vehicles, chemical plants and factories.

Particle pollution is a mix of tiny solid and liquid particles. Particle pollution is visible when trucks spew a dirty stream of exhaust. Coarse particles, defined as those between 2.5-10 microns, are created by mechanical processes such as construction, demolition, mining and agriculture. Fine particles, less than 2.5 microns, primarily are created by chemical processes such as burning fossil fuels in factories, vehicle exhaust and burning wood.

A recent study calculated that air pollution is a greater threat to the risk of heart attack than cocaine. The reason is that many people are exposed to unhealthy air, compared with the relatively small number of those who use cocaine. Other factors with a lower heart-attack risk included extreme physical exertion, excess alcohol use and depression. Traffic and air pollution account for about 1 out of 8 heart attacks worldwide.

In an accompanying editorial, Dr. Andrew Baccarelli pointed out: “The important message here is that while an individual’s risk from air pollution is moderate or small, each of us is exposed, making the amount of risk intolerable for the entire community.”

Air quality is improving. According to The American Lung Association, the nation’s 25 most-polluted cities improved their air quality in the previous year and 15 registered its best-ever lowest pollution levels.

However, ozone exposure even at levels deemed safe by current air standards can negatively affect lung function. There is direct correlation between higher ozone-level exposure and decrease in lung function.

Ozone pollution  can shorten life. Conversely, a drop in particle pollution between 1980 and 2000 lengthened life expectancy in 51 U.S. cities by an average of five months. Particle pollution is associated with increasing the risk of asthma, diabetes and chronic obstructive pulmonary disease (COPD).

Those most sensitive to the effects of air pollution are children, the elderly, people who work or exercise outdoors, and those with existing lung diseases such as asthma and COPD.

Ways to minimize pollution’s effects include staying indoors on poor air-quality days, keeping windows closed near busy roadways, use recirculated air in cars, and avoid exercising during morning and evening rush hours.