There are two main types of air pollution: ozone and particle pollution. Both are harmful to our health, and particle pollution, in particular, is associated with lung cancer. Particle pollution is a mix of solid and liquid particles, which are comprised of different chemicals and biological components. They come from burning wood, diesel and fossil fuels, says Janice Nolen, assistant vice president of National Policy at the American Lung Association and one of the authors of the organization's 18th Annual State of the Air report.

The particles that are most dangerous are the ones that are 2.5 microns or smaller (less than 1/7 the diameter of a human hair), says Dr. H. Kim Lyerly, George Barth Geller professor of cancer research at Duke University School of Medicine. "We breathe them in, and they don't pass out from the usual defense mechanisms [such as sneezing or coughing]. They get into the lungs and the blood stream."

Pollution, Lung Cancer and Other Health Problems

The International Agency for Research on Cancer, part of the World Health Organization, concluded in 2013 that particle pollution could cause lung cancer and classified particulate matter as a human carcinogen, or cancer-causing agent.

Experts aren't sure exactly what happens in the body when we inhale these particles. Many people are studying lung cancer and air pollution, especially particle matter, Lyerly says. While there's general agreement about the biology, the exact mechanism is not as clear. It appears from mouse studies that inhaling these particles changes our DNA. Particles may also play a role in chronic inflammation and the immune system. In addition to the association with lung cancer, we know pollution plays a role in heart disease, stroke, diabetes, mental health problems and other lung diseases. Both short-term and chronic, long-tem exposure to particle pollution is harmful.

Furthermore, people who already have lung cancer appear to be at increased risk for adverse health effects (including a shorter lifespan) when exposed to particle and ozone pollution.

How Do We Protect Ourselves From Air Pollution?

Individuals can take some steps to lower their exposure to pollution, but it's a complex subject that requires a concerted local, national – even international – effort. "It's a galvanizing topic," Lyerly says. "We all have to do things to reduce air pollution. Air pollution levels can be very dramatic in different cities, especially transportation hubs. Your distance from sources of pollution may drive decisions about where you exercise, and times and locations."

On a day-to-day level, you can (and should) stay indoors when your local Air Quality Index level is high (over 100 on a 500-point scale for individuals who are sensitive to pollution, such as those with heart or lung disease). The higher the AQI, the greater the immediate health risks. You can find the current AQI for your region from the Environmental Protection Agency's AirNow website or your local weather forecast.

You can also see how your community ranks nationwide in terms of pollution. According to the SOTA, 1 in 4 Americans lives in areas where pollution levels are often dangerous.

The good news is that our air quality has generally been improving over the past eight to 10 years, Lyerly says. Nolen says we've made enormous progress in reducing particle pollution. However, according to EPA research, there's still much we must do, from lowering power plant exhaust to switching to cleaner school buses so we don't expose children to diesel exhaust. The EPA has rules to help us transition to cleaner equipment and fuels, but it's a process, Nolen says.

The Clean Air Act

The Clean Air Act, established in 1970, regulates air emissions and authorizes the EPA to establish air quality standards to protect health and public welfare.

Nolen says the EPA recognized from the outset that we didn't know all we needed to about the health effects of pollution, so it required the EPA to review the science every five years and to use the most current data to set limits. "As a result," Nolen says, "we set stronger limits as we learn more and we're able to provide more protection for the public. The EPA knew the standards would drive the development of new technology. It's been one of the most powerful public health laws adopted."

It's not just about keeping the Clean Air Act intact, Nolen says. We must fund it, as well. We have to have the money to do the work of monitoring and implementing strategies to keep the air clean.

Clean air is important to everyone's health. "Just because you don't have lung cancer, doesn't mean air quality doesn't affect you," Lyerly says.