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Screening Level Analysis Derrionsirales Polerilially Significaril I leahl'i Risk Irripacl In order to conduct our screening -level risk assessment we relied upon AERSCREEN, which is a screening level air quality dispersion model.' As discussed above, the model replaced SCREEN3, and AERSCREEN is included in the OEHHA and the California Air Pollution Control Officers Associated ("CAPCOA") guidance as the appropriate air dispersion model for Level 2 health risk screening assessments ("HRSAs").6,' A Level 2 HRSA utilizes a limited amount of site -specific information to generate maximum reasonable downwind concentrations of air contaminants to which nearby sensitive receptors may be exposed. If an unacceptable air quality hazard is determined to be possible using AERSCREEN, a more refined modeling approach is required prior to approval of the Project. We prepared a preliminary HRA of the Project's construction and operational health risk impact to residential sensitive receptors using the annual PM10 exhaust estimates from the EA's CalEEMod output files, provided within the Greenhouse Gas Emissions Assessment ("GHG Assessment") as Appendix F to the EA. Consistent with recommendations set forth by OEHHA, we assumed residential exposure begins during the third trimester stage of life.$ The EA's CalEEMod model indicates that construction activities will generate approximately 125 pounds of DPM over the 363-day construction period.9 The AERSCREEN model relies on a continuous average emission rate to simulate maximum downward concentrations from point, area, and volume emission sources. To account for the variability in equipment usage and truck trips over Project construction, we calculated an average DPM emission rate by the following equation: grams 124.6 lbs 453.6 grams 1 day 1 hour Emission Rate (second) = x x x = 0.00180 g/s second 363 days lbs 24 hours 3,600 seconds Using this equation, we estimated a construction emission rate of 0.00180 grams per second ("g/s"). Subtracting the 363-day construction period from the total residential duration of 30 years, we assumed that after Project construction, the sensitive receptor would be exposed to the Project's operational DPM for an additional 29.01 years. The EA's operational CalEEMod emissions indicate that operational activities will generate approximately 340 pounds of DPM per year throughout operation. Applying the same equation used to estimate the construction DPM rate, we estimated the following emission rate for Project operation: grams 340.0 lbs 453.6 grams 1 day 1 hour Emission Rate ( = x x x = 0.00489 g/s (second) 365 days lbs 24 hours 3,600 seconds 5 "AERSCREEN Released as the EPA Recommended Screening Model," U.S. EPA, April 2011, available at: httpljwww.epa.gov/ttn/scram/guidance/clarification/20110411 AERSCREEN Release Memo.pdf 6 "Risk Assessment Guidelines: Guidance Manual for Preparation of Health Risk Assessments." OEHHA, February 2015, available at: hops://oehha,ca,ov/media/downloads/crnr/2015uidancemanual,pdf. ' "Health Risk Assessments for Proposed Land Use Projects." CAPCOA, July 2009, available at: http://www.capcoa.orgZwp-content/uploads/2012/03/CAPCOA HRA LU Guidelines 8-6 09,pdf. s "Risk Assessment Guidelines: Guidance Manual for Preparation of Health Risk Assessments." OEHHA, February 2015, available at: hops://oehha,ca,ov/media/downloads/crnr/2015uidancemanual,pdf, p. 8-18. ' See Attachment A for health risk calculations.