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5.1 E:CONSTRUCTION EMISSIONS AND IMPACT ANALYSIS <br /> used with HARP-derived risk values for Diesel exhaust particulate2 for a 9-year exposure to <br /> determine the potential carcinogenic risk from Diesel exhaust during construction.3 <br /> The maximum modeled annual average concentration of Diesel exhaust PMlo at any <br /> location is 0.45 µg/m3. The cancer risk value obtained from HARP is 4.15x10-4 (derived <br /> OEHHA method). Adjusting the risk value by 9/70 to reflect a 9-year exposure yields an <br /> adjusted risk value of 5.34x10-5. Using the risk value and adjustment factors described <br /> above, the carcinogenic risk due to exposure to Diesel exhaust during construction activities <br /> is expected to be approximately 24 in one million. This risk estimate is above the <br /> significance level of 10 in one million. However,these impacts are highly localized near the <br /> project site. As shown in the attached annual average Diesel combustion PMlo isopleth <br /> diagram(Figure 5.1E-3), the area in which the risk may exceed 10 in one million(Diesel <br /> PM10 impact greater than or equal to approximately 0.2 µg/m3)barely extends 1 beyond the <br /> construction and laydown/parking areas and does not include any residences or sensitive <br /> receptors.This analysis remains conservative because, as discussed above,the modeled <br /> PM10 concentrations from construction operations are overpredicted by the AERMOD <br /> model. <br /> 2 See Section 5.1.2.8 for a discussion of the use of the HARP model to derive cancer risk values. <br /> 3 OEHHA, "Adoption of Air Toxics Hot Spots Program Guidance Manual for Preparation of Health Risk <br /> Assessments," 10/03/03, accessed at http://www.oehha.ca.gov/air/hot—spots/HRAguidefinal.html <br /> 5.1E 8 SAC/371322/082330017(LEC-5.1 E_AP PENDIX.DOC) <br />