Whats being done to control ground-level ozone?
Thanks to the Clean Air Act of 1970, the Environmental Protection Agency is required to monitor and set maximum allowable concentrations of so-called criteria air pollutants, a group that includes ground-level ozone (the others are particulate matter, carbon monoxide (CO), sulfur oxides, nitrogen oxides, and lead). In 1997, the EPA lowered the allowable levels of ground-level ozone to a maximum of 0.08 parts per million (ppm) over an 8-hour period during a single day. To be sure, the Clean Air Act has had an extremely positive impact on air quality since its inception. Regulating the maximum allowable concentration of ground-level ozone has led to a slow but steady decline of the pollutant. Most recently, the EPA reported that between 1990 and 2006, the national average for ground-level ozone has decreased by 9 percent. However, the American Lung Association estimates that one-third of Americans-approximately 99 million people-still live in communities with unhealthful levels of ozone.
