Federal and State Standards
The United States Environmental Protection Agency has set national air quality standards for PM10 and PM2.5, based on health research, identifying acceptable levels of ambient particulate matter. Currently, many parts of the western United States violate these standards. The State of California has established generally more stringent ambient (outdoor) air quality standards for PM10 and PM2.5.1 These standards define the maximum amount of particles that can be present in outdoor air without threatening the public’s health. The California Air Resources Board (CARB) adopted an annual average standard for PM10 of 20 µg/m3 (micrograms per cubic meter), and 12 µg/m3 for PM2.5. CARB also adopted a 24-hour standard PM10 of 50 µg/m3. PM10 levels in most areas of California exceed current state standards from a few to many times each year. El Dorado County is designated as a Non-Attainment Area for the state PM10 standard.2 The 24-hour PM10 standard was exceeded in El Dorado County in 2003 and 2008.
California’s ambient air monitoring network is one of the most extensive in the world, consisting of over 250 sites where air pollution levels are monitored and more than 700 monitors used to measure pollutant levels to demonstrate Attainment or Non-Attainment of national and state ambient air quality standards.3 State area designations for ten criteria pollutants: ozone, suspended particulate matter (PM10), fine suspended particulate matter (PM2.5), carbon monoxide, nitrogen dioxide, sulfur dioxide, sulfates, lead, hydrogen sulfide, and visibility reducing particles are updated annually by CARB. El Dorado County monitors are located at; South Lake Tahoe – Sandy Way, Cool – Hwy 193, Echo Summit, and Placerville – Canal St.