We are approving California’s air plans for fine particles, but our work is far from done. EPA will continue to hold the State accountable for bringing air quality up to national standards. Clean air is a critical human health issue in California. In large part, the solution will be found in moving quickly towards zero emission transportation systems.

—Jared Blumenfeld, EPA Regional Administrator for the Pacific Southwest

Over the past 10 years, at the worst monitors, PM_2.5 has improved by 14% in the San Joaquin Valley and by 43% in the South Coast. However, these areas continue to be two of the most polluted air basins in the nation. PM_2.5 is made up of small particles in the air that can penetrate deep into the lungs and worsen medical conditions such as asthma and heart disease, particularly in children and the elderly.

Reducing exposure helps reduce asthma, cardiovascular disease, emergency room visits, cancer and premature death. According to a 2010 California Air Resources Board (ARB) study, PM_2.5 exposure leads to 9,200 premature deaths annually in CA.

Diesel mobile sources such as trucks, construction equipment and marine vessels are the largest source of PM_2.5 in California. Trucks and buses account for about 40% of diesel emissions from all mobile sources. With its adverse meteorology and substantial pollution from trucks that carry produce and international imports to the rest of the nation, California faces a daunting task in reducing pollution, EPA notes.

In November 2010, EPA proposed to disapprove the South Coast and San Joaquin Valley PM2.5 air quality plans because they relied heavily on emissions reductions from several State diesel and marine vessel rules that had not been finalized or submitted to the EPA for review.

Now, the ARB is finalizing these precedent-setting rules, including the In-Use Diesel Truck and Bus rules; the Drayage Truck Rules; and the Ocean Going Vessels Clean Fuels rule. California is the only state in the nation to aggressively target diesel emissions from existing diesel engines. These truck and bus rules will impact almost a million vehicles that operate in California and will prevent an estimated 3,500 deaths annually.

The ARB has also revised the plans that were originally submitted to EPA to more accurately reflect emissions both now and into the future. For example, ARB performed field work to more accurately characterize the age of trucks and truck travel patterns in California, and collected data that showed they had overestimated usage and emissions from construction equipment. ARB also revised future emission forecasts to account for the economic recession and adjusted future growth based on economic forecasts by UCLA and the University of the Pacific.

As a result of these changes, future emissions are forecasted to be lower and fewer emissions reductions are needed for attainment. For the SJV, the effect of these changes is that about 18% fewer reductions are needed because of better estimates of activity and emissions from trucks and construction equipment and about 5% fewer reductions are needed due to the recession.

For the SC, about 5% fewer reductions are needed due to better estimates of activity and emissions from trucks and construction equipment and about 5% fewer reductions are needed due to the recession.

Also, dozens of state and local measures have been improved to further reduce fine particle pollution from specific industries and activities. For example, San Joaquin recently required air pollution control equipment for commercial charbroiling restaurants and prohibited burning of prunings from various agricultural crops at all times. South Coast cut allowable sulfur emissions from hundreds of industrial boilers in its landmark RECLAIM program, and strictly limited the amount of solvents allowed in commercial cleaning products. Many of these rules are the most stringent in the nation.

While these plans mark a milestone, and the State is currently working on air quality plans for the more stringent 2006 PM2.5 standard, ultimately Californians will need to move to newer technologies to reduce emissions, EPA said. The State and local districts have launched a number of grant and incentive programs to demonstrate and deploy near zero emitting technologies.

The proposed actions will be published in the Federal Register and will include a 30-day public comment period from the date of publication. EPA invites the public to submit comments on the proposals and to resubmit comments on the November 2010 proposals.