The World Health Organization now considers air pollution to be the greatest environmental risk to human health, killing about 7 million people a year globally. Particulate matter is a huge part of the problem-ultrafine particles that come from power plants, car engines, forest fires, even your backyard grill. Wood fire, a common heating system in Fairbanks, is what drives that areas otherwise healthy air (its super low in ozone, another pollutant) into be careful breathing that stuff. Its number three on the list of cities with the most year-round particle pollution.

Those supersmall particles are able to slip past your respiratory systems defenses and get into your bloodstream, where they then cause trouble all over your body. In addition to lung problems such as asthma, these particles have been implicated in Alzheimers disease and other dementias, as well as heart disease and even diabetes.

If you live in one of the worst cities for breathing, youre not doomed. But you should double down on these strategies to lower your exposure . See how your city ranks, according to the newest info from the American Lung Association:

See the full list of best and worst cities here.