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5.1 AIR QUALITY <br /> 5.1.1.3.7 Particulate Sulfates <br /> Particulate sulfates are the product of further oxidation of SO2. The San Joaquin Valley Air <br /> Basin is in attainment of the state standard for sulfates (24-hour average <25µg/m3). There is <br /> no federal standard for sulfates. <br /> Due to extremely low ambient levels, sulfates have not been monitored in San Joaquin <br /> County at least since 1990. Table 5.1-7 presents maximum 24-hour average sulfate levels <br /> recorded in Bakersfield,the monitoring station closest to the project site,for the period <br /> 1995-2002,after which sulfate monitoring ceased at that station. During the period 1995-2002, <br /> sulfate levels in Bakersfield have been only about 17 percent of the state standard. <br /> TABLE 5.1-7 <br /> Particulate Sulfate Levels in Bakersfield, 1995-2002(micrograms per cubic meter) <br /> 1995 1996 1997 1998 1999 2000 2001 2002 <br /> Highest 24-hour Average 4.3 3.5 3.5 3.5 3.7 3.7 3.6 3.9 <br /> Number of Days <br /> Exceeding State Standard 0 0 0 0 0 0 0 0 <br /> (25 Ng/m3, 24-hour) <br /> Source: California Air Quality Data, Annual Summary, California Air Resources Board <br /> 5.1.1.3.8 Fine Particulates (PM10 and PM2.5) <br /> Particulates in the air are caused by a combination of wind-blown fugitive dust; particles <br /> emitted from combustion sources (usually carbon particles); and organic, sulfate,and nitrate <br /> aerosols formed in the air from emitted hydrocarbons, sulfur oxides, and nitrogen oxides. In <br /> 1984,the CARB adopted standards for fine particulates (PM1o), and phased out the total <br /> suspended particulate (TSP) standards that had previously been in effect. PM10 standards <br /> were substituted for TSP standards because PM10 corresponds to the size range of inhalable <br /> particulates related to human health. In 1987,EPA also replaced national TSP standards with <br /> PM10 standards. For air quality planning purposes,the San Joaquin Valley Air Basin is <br /> considered to be in nonattainment of both federal and state PM10 standards. <br /> Table 5.1-8 shows the federal and state air quality standards for PM1o,maximum levels, and <br /> arithmetic annual averages recorded at Stockton-Hazelton in Stockton from 1998 through <br /> 2007. Maximum 24-hour PM10 levels from this site frequently exceed the state standards,but <br /> have not exceeded the federal standard. Annual average PM10 levels are above the state <br /> standard during the monitoring period. <br /> The trend of maximum 24-hour average PM10 levels is plotted in Figure 5.1-8, and the trend <br /> of estimated violations of the state 24-hour standard of 50µg/m3 is plotted in Figure 5.1-9. <br /> Note that since PM10 is generally measured only once every six days, expected violation days <br /> are usually about six times the number of measured violations. The trends of maximum <br /> annual average PM10 readings and the California standard are shown in Figure 5.1-10. <br /> Annual average PM10 concentrations are above the state standard of 20µg/m3. <br /> SAC/371322/082410013(LEC_5.1_AIR_QUALITY.DOC) 5.1-15 <br />