STANISLAUS COUNTY — Authorities have called an Air Alert from Monday through Wednesday, saying residents need to be aware of rising ozone levels as school begins and traffic increases.
About 80 percent of the valley's ozone is caused by vehicle use, according to the San Joaquin Valley Air Pollution Control District, and during back-to-school week, vehicle idling is a major air-quality concern.
The district, which includes the counties of Stanislaus, San Joaquin, Merced, Madera, Fresno, Kings, Tulare and portions of Kern, announces the alerts in hopes that motorists avoid idling their cars and using drive-through services. Residents are encouraged to carpool.
School has started in most of Stanislaus County. Classes are scheduled to begin Monday in Turlock and Wednesday in Keyes.
In addition to reducing their driving during Air Alerts, residents are asked to shift ozone-creating activities, such as mowing and edging lawns with gasoline-powered equipment, to earlier in the day.
"In the past couple of years, we have had an extraordinary level of cooperation by the public," said Seyed Sadredin, district executive director, in a news release.
The cooperation could help the area achieve the one-hour federal ozone standard that has proved elusive for many years. Through vehicle registration fees, motorists are paying most of a $29 million annual penalty for missing the cleanup deadline on the standard.
Ozone is a corrosive gas that damages the lungs, eyes and skin. Health experts say ozone can trigger lung and heart ailments as well as early mortality.
The one-hour federal ozone standard was abolished in 2005, but air districts still must achieve the defunct threshold or face penalties. The valley's air regularly exceeds the more stringent eight-hour federal ozone standard, which has cleanup deadlines in the next decade.
Ozone forms best in hot, sunny, stagnant conditions. Air quality was better early in August after the July heat wave broke and temperatures dropped into the 90s for several days. But near-100-degree days and ozone problems have returned.
To receive notification of an Air Alert, call the district at (800) 766-4463 or subscribe to a free, automated email list at http://valleyair.org. To learn more, call the district's Modesto office, (209) 557-6400.