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KLEINF'EL®ER <br /> \� Bright People.Right Solutiom <br /> 4 RISK CHARATERIZATION <br /> Risk characterization refers to the process of quantifying the risk associated with a <br /> 1 given exposure to a toxic air pollutant. The focus of this HRA is the inhalation pathway <br /> as the primary exposure route for diesel PM. The approved California Air Resources <br /> Board risk assessment health values for diesel PM include cancer and chronic factors of <br /> j3.0E-04 and 5.0E+00, respectively. To determine the risk results, these factors are <br /> multiplied by the associated concentration value provided by the AERMOD model. For <br /> residents, the exposure is assessed based on 24 hours per day, 7 days per week for 70 <br /> years. For workers, the exposure is based on 50 years, 8 hours per day, 5 days per <br /> week. Thus, the risk to the workers is 16% of the risk to the residents. <br /> The risk results are shown in Table 2 and depicted graphically in Figure 3. The results do <br /> not exceed a cancer risk of 10 in a million or a Health Index of 1.0. A list of the results for <br /> each receptor is included in Attachment A. <br /> Table 2 <br /> Diesel HRA Results <br /> Modeled Health Risk <br /> Year <br /> Criteria Location Meteorology UTM' Concentration Result Thresholds <br /> (µg/mn3) <br /> 42028 <br /> Cancer 4202813 <br /> MEIR 2008 .4, 0.0276 8.28E-06 10.00E-06 <br /> Risk 653277.8, <br /> MEN 2008 4202905 0.0444 2.10E-06 10.00E-06 <br /> EMEIR 2008 653160.4, 0.0276 0.138 1 <br /> Chronic 4202813 <br /> Hl MEIW 2008 5342029057.8 0.0444 0.036 1 <br /> MEIR—maximum exposed individual resident <br /> MEW—maximally-exposed individual worker <br /> µg/m^3—micrograms per meter cubed <br /> Universal Transverse Mercator(UTM)coordinates are in meters and are based on the North American 1983 CONUS <br /> Datum,UTM Zone 10, Northern Hemisphere. <br /> 121339/IRV11 Rxxx Page 6 of 7 September 15, 2011 <br /> Copyright 2011 Kleinfelder <br />