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10 <br /> <br />the SCAQMD’s specific numeric threshold of 10 in one million.15 Thus, the DEIR cannot conclude less <br />than significant health risk impacts resulting from Project construction without quantifying emissions to <br />compare to the proper threshold. Screening-Level Assessment Indicates Significant Impact <br />In an effort to demonstrate the potential risk posed by Project construction and all Project operation to <br />nearby sensitive receptors, we prepared a simple screening-level HRA. The results of our assessment, as <br />described below, provide substantial evidence that the Project’s construction and operational DPM <br />emissions may result in a potentially significant health risk impact not previously identified by the DEIR. <br />In order to conduct our screening level risk assessment, we relied upon AERSCREEN, which is a screening <br />level air quality dispersion model. 16 The model replaced SCREEN3, and AERSCREEN is included in the <br />OEHHA 17 and the California Air Pollution Control Officers Associated (CAPCOA)18 guidance as the <br />appropriate air dispersion model for Level 2 health risk screening assessments (“HRSAs”). A Level 2 HRSA <br />utilizes a limited amount of site-specific information to generate maximum reasonable downwind <br />concentrations of air contaminants to which nearby sensitive receptors may be exposed. If an <br />unacceptable air quality hazard is determined to be possible using AERSCREEN, a more refined modeling <br />approach is required prior to approval of the Project. <br />We prepared a preliminary HRA of the Project’s construction and operational health-related impact to <br />residential sensitive receptors using the annual PM10 exhaust estimates from CalEEMod. For the <br />Project’s construction emissions, we used the CalEEMod output files provided in the DEIR. For the <br />Project’s operational emissions, we used SWAPE’s updated operational CalEEMod output files and <br />subtracted SWAPE’s updated existing (passenger cars) and updated existing (trucks) CalEEMod output <br />files. According to the DEIR, the closest sensitive receptor is located approximately 440 meters south of <br />the Project site (p. 5.2-11). Consistent with recommendations set forth by OEHHA, we assumed <br />exposure begins during the third trimester stage of life. The Project’s construction CalEEMod output files <br />indicate that construction activities will generate approximately 507 pounds of diesel particulate matter <br />(DPM) over the 795-day construction period. The AERSCREEN model relies on a continuous average <br />emission rate to simulate maximum downward concentrations from point, area, and volume emission <br />sources. To account for the variability in equipment usage and truck trips over Project construction, we <br />calculated an average DPM emission rate by the following equation: <br /> <br />15 “South Coast AQMD Air Quality Significance Thresholds.” SCAQMD, April 2019, available at: <br />http://www.aqmd.gov/docs/default-source/ceqa/handbook/scaqmd-air-quality-significance- <br />thresholds.pdf?sfvrsn=2 <br />16 “AERSCREEN Released as the EPA Recommended Screening Model,” USEPA, April 11, 2011, available at: <br />http://www.epa.gov/ttn/scram/guidance/clarification/20110411_AERSCREEN_Release_Memo.pdf <br />17 “Risk Assessment Guidelines Guidance Manual for Preparation of Health Risk Assessments.” OEHHA, February <br />2015, available at: https://oehha.ca.gov/media/downloads/crnr/2015guidancemanual.pdf <br />18 “Health Risk Assessments for Proposed Land Use Projects,” CAPCOA, July 2009, available at: <br />http://www.capcoa.org/wp-content/uploads/2012/03/CAPCOA_HRA_LU_Guidelines_8-6-09.pdf