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5.9 PUBLIC HEALTH 5.9.4.4 Public Health Impact Study Methods Emissions of non-criteria pollutants from the project were estimated using emission factors approved by the SJVAPCD, CARB, and EPA. Air dispersion modeling combined the emissions with site-specific terrain and meteorological conditions to estimate short-term and long-term arithmetic mean concentrations in air for use in the health risk assessment. The EPA-recommended air dispersion model,AERMOD,was used along with five years (2000-2004) of compatible meteorological data assembled and provided by the staff of the SJVAPCD. The meteorological data combined surface measurements made at Stockton Metropolitan Airport with upper air data from Oakland Airport. Because HARP is built on a previous EPA-approved air dispersion model,Industrial Source Complex Short Term, Version 3 (ISCST3),a special method was used to integrate the air dispersion modeling output from the required air dispersion model,AERMOD,with the risk calculations in the HARP risk module.15 The following paragraphs describe the procedures used to prepare this risk assessment. 5.9.4.4.1 Modeling Inputs In order to use AERMOD modeling results with the HARP model,the following adjustments were made: • The risk assessment module of the HARP model was run using unit ground level impacts (1 µg/m3) as the input concentration for each TAC to obtain derived cancer risks for each TAC;16 • Cancer risks were obtained from the HARP model for the Derived (OEHHA) Method (for residential exposure) and the Derived (Adjusted) Method (for worker exposure); • The HARP model output was cancer risk by pollutant and route for each type of analysis,based on an exposure of 1.0µg/m3 (i.e.,individual TAC cancer risks are expressed by the HARP model in units of risk perµg/m3 of exposure); • To calculate the total risk for the project,the annual average emission rate in g/s for each TAC and each individual equipment unit were multiplied by the individual cancer risk output from the HARP model for that TAC in (µg/m3)-1; and • The resulting weighted cancer risks for each TAC in units of (risk-g/s)/(µg/m3) were then summed for the emitting unit (see Appendix 5.11),Tables 5.113-2 and 5.1D-4),and the weighted totals were used as inputs to the AERMOD model as described below. An identical approach was used to determine the acute and chronic health impacts associated with the project (see Air Quality Appendix 5.1D,Tables 5.1D-3 and 5.1D-5). 5.9.4.4.2 Risk Analysis Method The screening analysis for the criteria pollutant modeling analysis was performed using the AERMOD model,the 2000 through 2004 Stockton meteorological data, specific receptor grids,and the stack parameters for operating cases at three different ambient temperatures. 15 Although CARIB has recently provided an`on-ramp"designed to allow HARP to be used with AERMOD,the software was considered too new to use in this analysis. 16 Procedure is described in Part B of Topic 8 of the HARP How-To Guides: How to Perform Health Analyses Using a Ground Level Concentration. SACI371322I082340007(LEC_5.9_PUBLIC_HEALTH.DOC) 5.9-15