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OEHHA22 and the California Air Pollution Control Officers Associated ("CAPCOA" )` guidance as the appropriate air dispersion model for Level 2 health risk screening assessments ("HRSAs"). 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 -related impact to residential sensitive receptors using the annual PM10 exhaust estimates from the SWAPE CalEEMod output files. Consistent with recommendations set forth by OEHHA, we assumed residential exposure begins during the third trimester stage of life. SWAPE's CalEEMod model indicates that construction activities will generate approximately 188 pounds of DPM over the 636-day construction period. 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 188.4 lbs 453.6 grams 1 day 1 hour Emission Rate = x x x = 0.001556 g/s second 636 days lbs 24 hours 3,600 seconds Using this equation, we estimated a construction emission rate of 0.001556 grams per second ("g/s"). Subtracting the 636-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 28.26 years, approximately. The Project's operational CalEEMod emissions indicate that operational activities will generate approximately 64 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 64.4 lbs 453.6 grams 1 day 1 hour Emission Rate (second) 365 days X lbs X 24 hours X 3,600 seconds — 0.000926 g/s Using this equation, we estimated an operational emission rate of 0.000926 g/s. Construction and operational activity was simulated as a 2.72-acre rectangular area source in AERSCREEN with dimensions of 157 by 70 meters. A release height of three meters was selected to represent the height of exhaust stacks on operational equipment and other heavy-duty vehicles, and an initial vertical dimension of one and a half meters was used to simulate instantaneous plume dispersion upon release. An urban meteorological setting was selected with model -default inputs for wind speed and direction distribution. The AERSCREEN model generates maximum reasonable estimates of single -hour DPM concentrations from the Project site. EPA guidance suggests that in screening procedures, the annualized average 22 "Risk Assessment Guidelines Guidance Manual for Preparation of Health Risk Assessments." OEHHA, February 2015, available at: htti)://oehha.ca.aov/air/hot spots/2015/2015GuidanceManual.pdf 23 CAPCOA (July 2009) Health Risk Assessments for Proposed Land Use Projects, htti)://www.cal)coa.ora/wp- content/uploads/2012/03/CAPCOA HRA LU Guidelines 8-6-09.pdf. 16 75C-91