May 16, 2013

San Diego County Meets National Air Quality Standard for Smog

LOS ANGELES – The U.S. Environmental Protection Agency announced that San Diego County has met the 1997 national health-based air quality standard for smog, also known as ground-level ozone. In addition, EPA has approved the state’s plan to maintain clean air standards for the more than three million residents of the San Diego area.


“This is a victory for San Diego County residents, who are now breathing the cleanest air in more than six decades,” said Jared Blumenfeld EPA’s Regional Administrator for the Pacific Southwest. “EPA will continue our collaboration with the state and the local air district to build on these improvements as we meet the challenge of the more protective 2008 ozone standard.”

Over the past decade, smog forming pollution, nitrogen oxide (NOx) and volatile organic compounds (VOC) have been reduced dramatically in San Diego County. Federal, state and local agencies have adopted emissions standards and implemented innovative programs that have reduced NOx by 25% and VOC by 15%. California cars, trucks and sports utility vehicles today produce 80% less smog forming pollution than they did 15 years ago.

“This accomplishment demonstrates that, in spite of population growth and increases in the numbers of motor vehicles, we can and will continue to make progress toward clean, healthy air, while maintaining a healthy economy,” said Robert Kard, Director of the San Diego County Air Pollution Control District.


Today’s announcement is based on clean air monitoring data captured since 2009 that show San Diego County meets the 0.08 parts per million federal standard for ozone. Data come from monitoring sites located throughout the County with the majority in the metropolitan area.

Despite today’s significant milestone, the area continues to strive to attain for the more stringent 0.075 parts per million ozone standard adopted in 2008.

Ground-level ozone is formed when NOx and 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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