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<br /> <br />2/6 <br /> <br />Outdoor Air Quality - To the maximum extent practicable, individual and common exterior <br />open space, including playgrounds, patios, and decks, shall either be shielded from the <br />source of air pollution by buildings or otherwise buffered to further reduce air pollution for <br />project occupants. <br />This HRA is prepared in accordance with the requirements in MM 4.B-4, above. Because the Project <br />would not introduce any new stationary sources of TAC emissions, such as a standby diesel generator, <br />the proposed project residents would only be exposed to TAC emissions from existing and foreseeable <br />future sources in the Project’s vicinity. Health risk impacts from these sources are summarized in the <br />memorandum. <br />BAAQMD HEALTH RISK THRESHOLDS <br />The BAAQMD recommends health risk screening thresholds in the current CEQA Guidelines, which <br />were updated in May 2017.1 The applicable screening thresholds for the Project are summarized <br />below: <br /> BAAQMD Health Risk Screening Thresholds <br />Risks and Hazards <br />for New Receptors Cumulative Threshold <br />Cancer Risk Increased cancer risk of >100 in a million (from all local sources) <br />Hazard Index (HI) Increased non-cancer risk of >10 HI (from all local sources) (chronic) <br />Ambient PM2.5 <br />Concentration <br />Ambient PM2.5 increase: > 0.8 µg/m3 annual average (from all local <br />sources) <br />Abbreviations: <br />HI = Hazard Index <br />PM2.5 = Particulate Matter less than 2.5 microns <br />µg/m3 = micrograms per cubic meter. <br /> <br />Reference: <br />BAAQMD, 2017. CEQA Air Quality Guidelines. May. <br /> <br />CUMULATIVE HEALTH RISK ASSESSMENT <br />In accordance with BAAQMD CEQA guidelines and Recommended Methods for Screening and Modeling <br />Local Risks and Hazards, Ramboll conducted a cumulative HRA for the new onsite sensitive receptors <br />(the Project’s residents). The BAAQMD recommends evaluating the potential sources of TAC emissions <br />within 1,000 feet of sensitive receptors and provides tools with conservative estimates of impacts from <br />these sources, including a stationary source tool and raster files for railways major streets, and <br />highways. The cumulative assessment tabulates the health risk impacts from existing offsite sources <br />(stationary and mobile) at the on-site sensitive receptor locations. The HRA considered any <br />foreseeable future sources of TAC sources in the Project’s vicinity. In addition to the evaluation of <br />each single source, the combined health risk from all sources emitting TAC and particulate matter less <br />than 2.5 microns in size (PM2.5) are evaluated. <br /> <br />1 BAAQMD, 2017. California Environmental Quality Act (CEQA) Air Quality Guidelines. May. <br />Appendix B Page 43