Are you one of the 1/3 of Americans who live in a smoggy city? Smog -- a heavy, dark fog primarily composed of ozone -- can trigger asthma symptoms, cause coughing, chest pain, wheezing, or even premature death. The top 10 smoggiest cities are:

• Los Angeles, CA. The air quality is slowing improving in LA, but, on average, it still has 90 days per year with unhealthy ozone levels.
• Bakersfield, CA. Bakersfield has an average of 83 days with unhealthy ozone levels each year, as well as other air quality issues.
• Visalia, CA. Lying near Sequoia National Forest, Visalia has an average of 68 high ozone days per year.
• Houston, TX. Nearly 400,000 Houston residents have asthma -- a condition that can be exacerbated by the city's average of 36 unhealthy ozone days per year.
• Fresno, CA. In 2000, Fresno had 87 unhealthy ozone days. Now, the city is averaging only 34 unhealthy ozone days per year -- still high enough to land it in the top 10, but amazing progress.
• Sacramento, CA. The fifth city from California's Central Valley to make the list, Sacramento has an average of 25 unhealthy ozone days per year.
• Dallas, TX. Dallas has an average of 22 unhealthy ozone days per year.
• New York, NY. With such a constant flow of traffic, it's almost surprising that New York doesn't have more than an average of 12 unhealthy ozone days per year.
• Washington DC/Baltimore. Our capitol region has an average of 11 unhealthy ozone days per year.
• Baton Rouge, LA. Baton Rouge averages 11 unhealthy ozone days per year.
  

So do you live in one of the top 10 cities? If so, or if you live in another area with its fair share of ozone issues, you should take measures to minimize your exposure. According to the American Lung Association, you can help protect yourself from ozone by:

• Checking weather reports for high air pollution warnings
• Avoid exercising near high traffic areas
• Exercise indoors on high pollution days
• Don't smoke indoors
• Minimize use of fireplaces/wood-burning stoves.
  
  

You can also do your part by minimizing your impact on the environment. Drive less by biking, walking, taking mass transit, telecommuting, or carpooling. Gas up your car when the weather is cooler and don't top off the tank (it releases more gas fumes into the air).