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4. ENVIRONMENTAL ANALYSIS 4.6 AIR QUALITY PARTICULATE MATTER — PM10 and PM 2.5 represent fractions of particulate matter that can be inhaled into the air passages and the lungs and can cause adverse health effects. Particulate matter in the atmosphere results from many kinds of dust-and fume-producing industrial and agricultural operations,fuel combustion, wood burning stoves and fireplaces, and atmospheric photochemical reactions. Some sources of particulate matter,such as demolition and construction activities and mining,are more local in nature, while others, such as vehicular traffic and wood burning stoves and fireplaces,have a more regional effect. Very small particles of certain substances(e.g.,sulfates and nitrates)can cause lung damage directly,or can contain adsorbed gases(e.g.,chlorides or ammonium)that may be injurious to health. Particulates also can damage materials and reduce visibility. Dust comprised of large particles (diameter greater than 10 microns)settles out rapidly and is easily filtered by human breathing passages. This dust is of concern more as a soiling nuisance than as a health hazard. The remaining fraction,PM10 and PM2.5,are a health concern particularly at levels above the federal and state ambient air quality standards. PM2.5 (including diesel exhaust particles) is thought to have greater effects on health,because these particles are so small and thus, they are able to penetrate to the deepest parts of the lungs. Scientific studies have suggested links between fine particulate matter and numerous health problems including asthma,bronchitis,acute and chronic respiratory symptoms such as shortness of breath and painful breathing. Children are more susceptible to the health risks of PM2.5 because their immune and respiratory systems are still developing. _ In 1983, the CARB replaced the standard for"suspended particulate matter"with a standard for suspended PM10 or"respirable particulate matter." This standard was set at 50 micrograms per — cubic meter(µg/m3)for a 24-hour average and 30 µg/m'for an annual average. The CARB revised the PM10 standard in 2002,pursuant to the Children's Environmental Health Protection Act. The revised PM10 standard is 20 µg/m3 for an annual average. In addition, the CARB — adopted a PM2.5 standard set at 12 µg/m3 for an annual average. TOXIC AIR CONTAMINANTS Toxic air contaminants(TACs) are pollutants that are associated with acute, chronic, or carcinogenic effects but for which no ambient air quality standard has been established. TAC impacts are evaluated by determining if a particular chemical poses a significant risk to human health and, if so,under what circumstances. The ambient background of TACs is the combined result of many diverse human activities, including gasoline stations,refineries,automobiles, industrial operations, and painting operations. In general,mobile sources(such as diesel) contribute more significantly to health risks than stationary sources. RMC Pxific Vemalis Quauy Mining and Reclamation Pmjecl 4.6-6 ESA/203015 Adminisualive Draft ER Manch 2004