By Katrina Marland

I’m going to let you in on a secret: air pollution is bad for you. Okay, so it isn’t much of a secret at all, but it also isn’t something people often think about. Short of Los Angeles-type clouds of smog, it isn’t something that the average person can always see — or even smell. Out of sight, out of mind, so to speak.

What’s becoming harder to ignore is the threat to our health. A new study, recently published in the American Journal of Respiratory and Critical Care Medicine, has come out with a sobering fact: air pollution is the sixth leading cause of cancer in the U.S.

We no longer live in an era where not smoking can mean that you probably won’t get lung cancer; now, one in 10 cases of lung cancer occurs in someone who has never smoked. In fact, a person living in an area with higher pollution is about 20 percent more likely to die from lung cancer than someone breathing cleaner air.

It doesn’t stop there. According to the World Health Organization’s data from 2004-2008, lung cancer accounts for only 20 percent of air-pollution-related deaths in the U.S., with tens of thousands more attributed to other cardiopulmonary diseases. Take a look at the data on their interactive map of air pollution mortality rates.

What’s most disturbing about these findings? To me, it is the fact that, although there are many actions we can take as individuals to minimize the amount of pollution we put into the air, some of it is simply outside of our control. Many companies and corporations are contributing a great deal to these health-threatening levels of pollution, and they may or may not be particularly concerned with my health or yours.

In 2010, it is estimated that the Clean Air Act saved 164,000 lives and prevented thousands of cases of bronchitis, asthma attacks and other related conditions. There’s been a lot of talk about overregulation this year, complaints that the EPA’s guidelines are too much of a burden on businesses and scoffs at the environmental organizations suing the EPA for failing to tighten its regulations. While some thought does need to be given to the economic impact of such regulations, I wonder how much “overregulation” can really be taking place when we’re seeing increasing proof that the air we’re breathing is literally toxic.

What’s the pollution like in your hometown? You can see on NPR’s new Poisoned Places map.