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Munn&Perkins Quarry Excavation Permit r- the carbon monoxide state and federal standards. CO measurements and modeling were important in the early I980's when CO levels were regularly exceeded throughout California. In more recentY ears, CO measurements and modeling have not been a priority in most California air districts due to the retirement of older polluting vehicles, less emissions from new vehicles and improvements in fuels. The clear success in reducing CO levels is evident in the first paragraph of the executive summary of the California Air Resources Board 2004 Revision to the California State Implementation Plan for Carbon Monoxide Updated Maintenance Plan for Ten Federal Planning Areas(ARB,2004), shown below: « v- The dramatic reduction in carbon monoxide(CO)levels across California is one of the biggest success stories in air pollution control.Air Resources Board(ARB or Board) requirements for cleaner vehicles,equipment and fuels have cut peak CO levels in half since 1980,despite growth. All areas of the State designated as non-attainment for the federal 8-hour CO standard in 1991 now attain the standard, including the Los Angeles urbanized area.Even the Calexico area of Imperial County on the congested Mexican -- border had no violations of the federal CO standard in 2003. Only the South Coast and Calexico continue to violate the more protective State 8-hour CO standard, with declining levels beginning to approach that standard." Respirable Particulate Matter(PM10 and PM2.5).PM10 and PM2.5 consist of particulate matter that is 10 microns or less in diameter and 2.5 microns or less in diameter,respectively. (A micron is one-millionth of a meter). PM10 and PM2.5 represent fractions of particulate matter that can be inhaled into the air passages and the lungs and can cause adverse health effects. Some sources of particulate matter,such as wood burning in fireplaces,demolition,and construction activities, are more local in nature,while others,such as vehicular traffic,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.Large dust particles(diameter greater than 10 microns)settle out rapidly and are easily filtered by human breathing passages. This large dust is of more concern as a soiling nuisance rather than a health hazard.The remaining fraction, PM 10 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,are able to penetrate to the deepest parts F 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 andainful breathing.Recent studies have shown an association between p g morbidity and mortality and daily concentrations of particulate matter in the air. Children are more . susceptible to the health risks of PM10 and PM2.5 because their immune and respiratory systems , are still developing. Mortality studies since the 1990s have shown a statistically significant direct association between �r mortality (premature deaths) and daily concentrations of particulate matter in the air. Despite important gaps in scientific knowledge and continued reasons for some skepticism,a comprehensive evaluation of the research findings provides persuasive evidence that exposure to fine particulate Munn 8 Perkins Quarry Excavation Permit 3.3-4 ESA 1211086 Draft EIR April 2011 C.