High ozone levels in the Valley have prompted an extension of Wednesday's air alert through today.
Although better weather conditions are anticipated for today, the air basin still faces the possibility of exceeding the federal one-hour ozone standard, the San Joaquin Valley Air Pollution Control District said. This week's alert is the fourth of the season.
The Valley saw a second violation of the one-hour ozone standard in Clovis and a third violation in south Fresno this year.
Air alerts are called when conditions could lead to ozone levels that potentially exceed the federal one-hour ozone standard of 125 parts per billion. Multiple violations of the ozone standard can result in financial penalties.
The air alert is in effect for the counties of Fresno, Kings, Tulare, Madera, Merced, Stanislaus and San Joaquin and portions of Kern County.