Walking outside is my favorite way to exercise, so I was disturbed to read this article about athletes in Bakersfield, CA. Bakersfield sits near the top of the list of the countries most polluted cities, and it's elite outdoor athletes are feeling it. Athletes take in far more air when working out that those who are sedentary and that elevated level of air pollution can have an effect on the heart and lungs. The problem lies not only with ozone, but with fine particulates, which are found in car, truck, and diesel exhaust. The particulates irritate the lungs and work their way into the bloodstream where they can damage the heart.

It's all enough to make you stay inside where it's nice and safe, isn't it? Health experts say you don't have to, but that it might be in your best interest to pay attention to where and when you're working out. Stay off roads with heavy traffic and work out indoors when the air quality is bad. Most states have websites that let you check your air quality index, and if they don't, here's a less specific national map.