Local air leaders are poised Thursday to announce the Valley has attained a federal ozone standard, a health landmark and a new symbol of hope in a region notorious for bad air.
The announcement at the San Joaquin Valley Air Pollution Control District also will touch on a $29 million annual fee related to the one-hour federal ozone standard. Officials want to eliminate the mandate for the fee, paid mostly by a vehicle registration surcharge.
But the mandate will remain while the U.S. Environmental Protection Agency examines the district's case to be excused for problems in two Valley ozone hot spots. EPA can examine the evidence for up to a year.
Longtime district staffers are elated at the prospect of achieving the standard, which has seemed out of reach here for years. The Valley has long been among the worst ozone offenders in the country.
Spanning 25,000 square miles from Stockton to Bakersfield, this region is one of only two in the country designated as "extreme nonattainment" of the standard. The other is the Los Angeles-area South Coast Air Basin, which remains in violation.
The Valley is unlike any place in the country, say atmospheric chemistry experts. Hot summers promote ozone, and the bowl shape can keep it trapped for days, allowing bad air to build into high concentrations.
With cleaner fuels and vehicles as well as pioneering rules over such sources as farming, the air has improved dramatically since the 1990s. District leaders say air alerts have helped get the public involved in curbing polluting activities on bad-air days.
In 1996, which was among the worst air-quality years on record in the Valley, ozone remained above the standard for more than 280 hours. This year, it has not crossed the threshold, and the warm-weather ozone season has passed.
"I did not think it would happen in our lifetimes," said district executive director Seyed Sadredin. "It's so difficult to eliminate the last few problems. I think it was the air alerts that gave us the final push."
The one-hour standard was abolished in 2005 in favor of the more restrictive and health protective eight-hour standard. The Valley is still many years away from attaining that measure.
At the same time, federal law requires air districts to attain the old one-hour standard.
Environmentalists say the one-hour attainment really has not happened yet. Lawyer Paul Cort of the legal watchdog Earthjustice in San Francisco said EPA still needs to agree with the district's analysis of two ozone problems. Earthjustice has filed several air-quality lawsuits in the Valley over the past decade.
"There are huge questions to be answered," he said. "This announcement on Thursday is more of a publicity stunt than anything else."
The questions revolve around an exceedance at a Fresno ozone monitor in 2012 and the relocation of a Kern County ozone monitor in Arvin a few years ago.
The 2012 exceedance in Fresno would cause the Valley to remain in violation of the one-hour ozone standard. But district analysts say it was an "exceptional event" due to a fire at the Chevron refinery in Richmond and several Sierra wildfires that summer.
Fires send out ozone-making pollutants that drift into the Valley, analysts say.
The Arvin monitor case is a little more complex. The California Air Resources Board lost its lease for the longtime monitoring site, which recorded some of the Valley's worst ozone episodes in the past. The new site, two miles away at an elementary school, initially showed lower readings. Air activists complained loudly about it.
But during the summer this year, the district set up more than 20 temporary monitors in the Arvin area, including two next to the old monitoring site. Sadredin said readings at the elementary school -- which remained safely below the health threshold -- were higher this summer than the readings at the old site.
"We have a good case to make that we are taking a more conservative approach in demonstrating attainment," he said.
EPA regional leaders say they will study the district's analysis, which also includes the effect of ozone gases from China traveling across the Pacific Ocean to the Valley.
An EPA regional spokeswoman on Wednesday said: "The ball is in the district's court, and EPA is ready to work hands-on with the air district to do the required analysis as soon as they are ready to proceed."
If you go:
What: Valley air district board meeting
When: 9 a.m. Thursday
Where: 1990 E. Gettysburg Ave., Fresno
The reporter can be reached at (559) 441-6316, email@example.com or @markgrossi on Twitter.