Release 07-48
October 25, 2007

    Leo Kay
Patricia Rey
(916) 322-2990

ARB adopts San Joaquin Valley's PM10 Maintenance Plan

Improved Valley's air quality attains standards ahead of 2010 deadline

SACRAMENTO - In adopting the San Joaquin Valley's maintenance plan for addressing coarse particulate matter (PM 10) for 2007 today, ARB is now requesting the U.S.EPA to redesignate the area to attainment under the national ambient air quality standards.

"Meeting the PM10 standard is an important milestone. Maintaining the standard will require continued vigilance, but the combined efforts of local and state regulators with the cooperation and support of businesses and residents have demonstrated that the people of the Valley place a high priority on clean air," said ARB Chairman Mary D. Nichols.

Particulate matter is comprised of tiny particles made up of many different materials such as metals, soot, soil and dust, and can be formed in the atmosphere. PM may be divided into many size fractions, measured in microns (a micron is one-millionth of a meter). PM10 (up to 10 microns in size) includes smaller PM2.5 particles, both of which are linked to adverse health effects. Ambient air quality standards define the maximum amount of particles that can be present in outdoor air without threatening the public's health.

Due to the adoption of ARB and local air district rules, the Valley's air quality has improved to the point of attainment of the PM10 standards before the 2010 deadline. This important milestone also reflects the Valley's progress toward meeting the more stringent particulate matter standards for PM2.5.

Some of the local and state measures adopted in the past to reduce PM10 include among others, the curtailment of use of wood-burning fireplaces during periods with predicted high PM levels, dust controls for construction and agricultural operations, controls on local industries, emission standards for cars and trucks, California fuel regulations, and many more.

The San Joaquin Valley air board adopted the 2007 PM10 maintenance plan to address the Clean Air Act requirements and request official redesignation to attainment. ARB will now submit the plan to U.S. EPA as a revision to the State Implementation Plan. The federal agency has 18 months to act on the maintenance plan and request for redesignation. Since the maintenance plan must provide for continued attainment 10 years after designation, the local air district selected 2020 as the target maintenance year.

The Air Resources Board is a department of the California Environmental Protection Agency. ARB's mission is to promote and protect public health, welfare, and ecological resources through effective reduction of air pollutants while recognizing and considering effects on the economy. The ARB oversees all air pollution control efforts in California to attain and maintain health based air quality standards.