Does your city have trouble with ozone? Ozone is a pollutant that can cause respiratory problems, and if you're looking for a reason not to take shower today, you just may have found it. Researchers recently learned that greasy, unwashed hair absorbs seven times more ozone than clean hair. While it may not have a huge impact when you're outside on a high-ozone day, researchers said that the difference was big enough to clean up the air quality in your immediate vicinity.

Of course, you may be stuck at home a lot more often, since greasy, unwashed hair isn't going to make you very popular. In addition to that, though, the grease in the hair also reacts with ozone to make a by-product that might not be much better for you than the ozone itself.

So rather than changing your hygiene habits, health experts recommend filtering indoor air if you or someone in your home is elderly or has chronic health conditions.