To develop the rankings, the American Lung Association counted the number of days in each urban area in which the ozone standard was exceeded from 1997 to 1999. It ranked the severity of the excesses with a weighted score, divided by three and compared the results. Cities in North Carolina and the rest of the Southeast didn't fare well, said Tom Mather, a spokesman for the N.C. Division of Air Quality. Smog levels increased dramatically across the state during the brutally hot summers of 1998 and 1999. Ozone forms when nitrogen oxides and other pollutants bake in the sun.
Higher temperatures produce more ozone.
Unhealthy smog levels in the Triad, for instance, occurred on 35 days in 1998 and on 30 days in 1999. The rankings reflect the South's hot weather during the three-year period, admitted Steve Willcox, the chief executive of the N.C. Lung Association. Some metro areas in the Northeast and Northwest dropped in the rankings as Southern urban areas moved up. The five areas that made the list for the first time are in the South. There is something positive because they are doing some things about it in the state.