Environmental Protection

EPA Paves Way for New Ozone Plans for Nation’s Worst Two Air-Quality Zones

With the continuing goal of improving air quality for millions of Californians, the U.S. Environmental Protection Agency is proposing to approve the 8-hour ozone air quality plans for the San Joaquin Valley and South Coast areas. These plans, known as State Implementation Plans, are the roadmaps to meeting the Clean Air Act standard of 0.08 parts per million of ozone as measured in 8-hour increments.

“California’s air quality has improved dramatically since the Clean Air Act was approved by Congress more than forty years ago,” said Jared Blumenfeld, EPA’s regional administrator for the Pacific Southwest. “Today the Golden State is making a commitment to use clean technologies to solve the air quality challenges faced in the San Joaquin Valley and South Coast.”

The air districts are making steady progress toward meeting the 8-hour ozone standard, one of the National Ambient Air Quality Standards, by 2024. In 1997, EPA first established the 8-hour ozone standard, which replaced the older 1-hour ozone standard (0.12 ppm). The 8-hour standard is more protective of human health because it addresses the impacts of exposure over longer periods of time.

EPA is proposing to approve the 8-hour ozone air quality plans for the San Joaquin Valley and South Coast, which include their attainment demonstrations, enforceable commitments and reductions from new technologies.

There have been vast improvements in air quality in California over the previous decades. The worst sites in California have demonstrated a 52 percent improvement in ozone from 1976 to 2010, a 29 percent improvement in fine particulate matter (PM2.5) from 2001 to 2010, an 84 percent improvement in carbon monoxide from 1970 to 2009, and a 92 percent improvement in sulfur dioxide from 1970 to 2009.

In both areas, statewide measures such as the in-use truck and off-road diesel rules, and smog-check improvements will further reduce air pollution. In the San Joaquin Valley, district rules will reduce pollution from open burning, boilers, composting, and livestock operations. In the South Coast, the marine vessel rules and district rules targeting pollution from solvents, lubricants and boilers will reduce ozone pollution.

Ground-level ozone is formed when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the atmosphere in the presence of sunlight. NOx and VOCs are called ozone precursors. Motor vehicle exhaust, industrial emissions, and chemical solvents are the major sources of these chemicals. Ozone pollution is a concern especially when the weather conditions needed to form it—lots of sun and hot temperatures—occur. Ozone pollution can irritate airways, worsen asthma symptoms and increase hospitalizations for respiratory cases. Children and the elderly are most impacted by ozone pollution.

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