No. 1: Bakersfield, CaliforniaThe American Lung Association ranks Bakersfield as the city most polluted by year-round particle pollution. The area's dry, stagnant weather doesn't help matters either (nasty pollutants and no fresh, cool air to blow them away). This combined with Bakersfield's record-high sunshine and heat makes this Cali locale a combat zone for your skin. As Dr. Kunin explains, the actual particle pollution obviously isn't good for skin, but what's even more damaging is when the pollution depletes the ozone layer and allows stronger, more damaging UV rays to reach us (Bakersfield is the second most ozone-polluted city).