California Air Resources Board

SACRAMENTO –  With an eye towards better understanding of potential public health impacts, the California Environmental Protection Agency's Air Resources Board (ARB) has developed a new statewide monitoring network for measuring fine particulate matter measured at 2.5 microns in size or smaller. Referred to as PM 2.5 and about the 1/25 the width of a human hair, these inhalable particles result from a number of sources, including unburned fuels, tire dust and factory emissions.

        "We've made great progress in cleaning up California's air, but with this new public health challenge on the horizon to reduce particulates, we'll need accurate information," said ARB Executive Officer, Michael Kenny.  "This monitoring network is the first of its kind in the country, and what we learn will have worldwide benefit."

        In response to new federal standards for PM 2.5 announced in 1997, the PM 2.5 monitoring program will provide ambient data that support the state's air quality programs and provide a basis for future regulatory action. To date, ARB has deployed monitoring systems at 78 sites in California. Sites were chosen based on population, high concentration of PM 2.5 and geographic representation. ARB and local air quality management districts plan to add 14 more monitoring sites by the end of 1999.

        PM 2.5 particles are small enough to pass through the body's natural defenses and lodge deep within the lungs. In addition, PM 2.5 can attach to other fine particles, causing or enhancing illnesses such as asthma, emphysema, bronchitis, or even cancer.

        For more information about PM 2.5, please click here.