States with smog problems in 2007 through May (29 states plus DC)
District of Columbia
Factoids: Each state listed has recorded at least one monitor with ozone levels worse than current EPA standards. As usual, California had the most dirty-air days: 20 altogether. The highest daily ozone levels have been recorded in Houston (112 parts per billion, May 15) and Bucks County, PA (109 on May 31). The highest one-hour level (166) was recorded in the Houston area May 14. The most dirty-air days (8) at a single monitor have been recorded at Crestline in San Bernadino, CA. Vermont experienced a relatively rare problem May 25. The first monitored problem of the year took place March 16 in the Livingston Parish, LA.