In a historic vote, Valley air-quality leaders on Thursday asked federal officials to approve the region's attainment of the one-hour ozone standard.
A few years ago, the Valley achieved the federal PM-10 standard -- coarse particle pollution usually associated with dust -- but this would be the first time the region has ever achieved an ozone standard.
For the first time on record, the Valley did not record a violation of the one-hour ozone standard during the warm months when the problem occurs. The achievement seemed all but impossible 10 years ago.
The governing board for the San Joaquin Valley Air Pollution Control District credited businesses with investing $40 billion in clean air since the 1980s.
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Members also thanked the public for cooperating with air alerts.
The board's request now will be sent to the U.S. Environmental Protection Agency, which will study the district's explanation for issues in two ozone hot spots.
If EPA does not accept the explanation, the Valley would continue in violation of the one-hour ozone standard and still be liable for a $29 million annual fee, which was levied two years ago. The fee is paid mostly by motorists with a surcharge on vehicle registration.
The fee revenue remains in the Valley, going to pollution cleanup programs, such as replacing older diesel engines with new, cleaner-burning ones.
District executive director Seyed Sadredin said he would push for an EPA decision within a year.
Board member Judy Case, a Fresno County supervisor who has been on the air board for many years, acknowledged and applauded everyone's efforts to achieve the one-hour ozone standard.
"It's been a long, hard road," she said.
The district has passed more than 500 rules that have helped to reduce 80% of pollution emissions from sources in the district, including the petroleum and agriculture industries.
Even so, the Valley still is among the worst offenders of the newer, more stringent eight-hour ozone standard. Leaders said they knew the battle for clean air must continue.
"We've won a battle, but we haven't won the war yet," said board member William O'Brien, a Stanislaus County supervisor.
EPA officials this week said they will take a hard look at the district's request for a waiver of a Fresno exceedance of the one-hour ozone standard in 2012. The district said fires outside the area sent just enough pollution into the Valley to push the monitor into an exceedance.
The district also will include a study explaining an issue at the Kern County monitoring site in Arvin. The state lost its lease for the long-time Arvin site in 2010 and was forced to move it two miles away. The new monitor showed lower readings, raising a controversy.
For attainment of the ozone standard, the district needed to show that the new site works as a replacement for the old site, which had been notorious for high readings over many years.
The district set up many temporary monitors in the area this year. The new site now has higher readings than the old one, though both were below the health threshold -- meaning the new site may be in a better location to detect pollution, local air leaders said.
Kern County air activist Tom Frantz of Shafter predicted the EPA will not agree.
"We had a pretty good year for ozone, and that's good," he said. "But we have not made the standard yet."