Ready to be startled? Approximately one in ten people who develop lung cancer have never smoked. Researchers think it has to do with dangerous air pollution levels in the cities in which they reside.

Nonsmokers who live in areas with high air pollution levels are 20 percent more likely to die from lung cancer than people who live in places with cleaner air, according to a new study out of the University of Ottowa.

Lead author of the study Michelle Turner and her colleagues followed more than 180,000 non-smokers for 26 years and found that 1,100 people died from lung cancer.

Based on their zip codes, participants’ level of air pollution were measured in units of micrograms of particles per cubic meter of air. The researchers, who controlled for other cancer risk factors, found that for every 10 extra units of air pollution exposure, participants’ risk of lung cancer rose by 15 to 27 percent.

So what’s going on in our air? Tiny particles can act as agents causing irritation in the lungs and prompting inflammation as well as lung cancer.

And with a recent report noting that Philly had 29 days of dangerous air pollution levels last year, it’s not looking good for our city. Plus, three of those 29 days were in “red-alert” territory with pollution bad enough to cause adverse health affects. Yikes.

But keep in mind, people who smoke are still ten to 20 times more likely to get lung cancer or die from lung cancer than those who don’t. So while you’re avoiding the attack of air pollutants, steer clear of the second-hand smoke as well.