October 3rd Release:  The U.S. Environmental Protection Agency is approving California’s air quality plans for fine particles — known as PM2.5 — in the South Coast and San Joaquin Valley. These plans will reduce pollution to the level required by the health based 1997 PM2.5 standard by 2015.

Over the past 10 years, at the worst monitors, particulate matter has improved by 14% in the San Joaquin Valley and by 43% in the South Coast.  “Worst monitors” are those that have the highest annual average PM2.5 concentration for a three year period in the air basin.

PM2.5 is made up of small particulate matter—1/30th the diameter of a human hair. Fine particle pollution can be emitted directly or formed secondarily in the atmosphere and can penetrate deep into the lungs and worsen conditions such as asthma and heart disease. Reducing exposure helps reduce asthma, cardiovascular disease, emergency room visits, cancer and premature death. According to a 2010 California Air Resources Board study, PM2.5 exposure leads to 9,200 premature deaths annually in CA.

Mobile sources of diesel, such as trucks, construction equipment and marine vessels, are the largest source of PM2.5 in California. Trucks and buses account for 40% of the total diesel emissions. The state has adopted aggressive rules to target diesel emissions including the In-Use Diesel Truck and Bus rules, the Drayage Truck Rules and the Ocean Going Vessels Clean Fuels rule. The truck and bus rules are the first of their kind throughout the nation and will prevent an estimated 3,500 deaths.

EPA is disapproving the plans’ contingency measures because they do not provide sufficient emissions reductions.  EPA will continue to work with the state to resolve these remaining issues.

The South Coast and San Joaquin Valley suffer from some of the worst pollution in the nation, which is caused by myriad factors including adverse meteorology, ports activities and substantial pollution from trucks that carry produce and international imports to the rest of the nation.

The state is currently working on air quality plans to meet the more stringent 2006 PM2.5 standard. In addition, the state and local districts have launched grant and incentive programs to demonstrate and deploy near zero emitting technologies.

Today’s actions will be published in the Federal Register and will become effective 60 days from the date of publication. EPA’s Federal Register notices include detailed responses to all major comments on our proposed actions.

For more information on the South Coast and San Joaquin Air Quality Plans, please visit EPA’s web site at: http://www.epa.gov/region9/air/actions/ca.html