Ozone is a powerful poison, odorless and colorless. As if carbon monoxide and particulate matter aren't bad enough, ozone is a real killer. Ozone kills many people every year who are the weakest in our population.
In healthy people, ozone can permanently damage the lungs, burning them with a chemical oxidizing action similar to chlorine gas which was used to kill and cripple
soldiers in WWI. In athletes, the effect can be more damaging if the athlete exercises heavily and often in ozone-polluted air.
Where is ozone found? Where does it come from? How can you avoid it? Ozone is produced abundantly wherever there is sufficient sunlight and car exhaust, primarily on hot, sunny, urban and suburban afternoons. The safest period for exercise in areas congested with traffic is generally before 6 p.m. Ozone levels begin to rise around noon and can rise rapidly after 3 p.m. They can become unhealthy after 6 p.m. and can continue to rise even after dark, peaking as late as 9 or 10 p.m. Ozone levels can remain unhealthy until well after midnight.
In the summer, I always monitor my city's ozone levels. As a cyclist, I avoid the higher ozone levels by finishing my rides as early as possible, before 6 pm. I have experienced ozone irritation many times, mostly before I knew about the effects of ozone pollution and how to avoid it.
Don't wait until you feel the symptoms. Check your area's ozone levels through the EPA's AIRNOW website during the spring and summer. Air quality forcasts are given daily for many cities nationwide. Keep your lungs breathing deeply for cycling!
This is the webpage: