OPINION/COMMENTARY

Smog Hits a Record Low

2004 has had the lowest ozone smog levels since states began measuring the stuff back in the 1970s. Based on preliminary data from around the country, days exceeding EPA's tough new 8-hour ozone standard declined an average of about 50 percent below 2003, which was itself a record year.[1] A combination of continuing emission reductions and favorable weather explains the improvements. Weather is the single largest factor affecting year-to-year variations in smog levels. All else equal, cool, wet, and windy years will have less ozone than warm, dry, and calm ones. But weather is only part of the story. During the last 30 years most of the country has had several years that were cooler and/or wetter than 2004, but never have smog levels been anywhere near this low....