The San Joaquin Valley may be turning the corner on a decades-long struggle to reduce ground-level ozone pollution.
The San Joaquin Valley has some of the most unhealthy air in the state, primarily from ozone.
Under strict federal air quality standards for decades, the region has been aggressive in reducing ground-level ozone from trucks, cars, buses, construction and agricultural equipment.
"Over the past 5-to-7 years is where we've seen the biggest strides because of over $100 million in incentive programs that have also been implemented in replacing heavy duty diesel trucks and other diesel engines throughout the valley," says Anthony Presto, with the San Joaquin Valley Air Pollution Control District.
The San Joaquin Valley Air Pollution Control District tracks air quality for eight counties, including Stanislaus, San Joaquin and Merced, in the northern part of the Central Valley.
"All of the businesses, industry in the San Joaquin Valley have invested over $40 billion in the past 20 years to upgrade and replace equipment that emits some type of air pollution," says Presto.
Presto says the switch to cleaner operating engines by individuals and businesses in the San Joaquin Valley have helped reduce emissions from those sources of ozone by 80 percent.
And, for the first time in 20 years, the San Joaquin Valley had three weeks of healthy air in July.
Ground-level ozone comes primarily from cars, trucks, buses and construction and agricultural equipment.
In 2004, federal regulators said it would be unlikely the Valley would ever attain the one-hour ozone standard under the Clean Air Act.
But, in 2013, San Joaquin Valley had no violations, a major change from 1996, when the San Joaquin Valley experienced 281 violations of the hourly standard throughout the eight-county region.