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AUGUSTIN BERNAL MOUNTAIN BIKE TRAIL PROJECT DRAFT INITIAL STUDY considerable. If a project exceeds the identified significance thresholds, its emissions would be considered cumulatively considerable, resulting in significant adverse air quality impacts to the region's existing air quality conditions.Therefore, if the project's emissions are below the BAAQMD thresholds or screening criteria, then the project's cumulative impact would be less than significant. As described previously,criteria pollutant emissions generated byshort-term construction and long- term operations of the project would not exceed the BAAQMD significance thresholds. Thus, the project would have a less-than-significant cumulative impact in relation to regional emissions. In addition, project-related traffic would not exceed the BAAQMD CO screening criteria and would result in a less-than-significant cumulative impact with regard to localized CO. C) Would the project expose sensitive receptors to substantial pollutant concentrations? The BAAQMD has adopted project and cumulative thresholds for three risk-related air quality indicators for sensitive receptors: cancer risks, noncancer health effects, and increases in ambient air concentrations of PM2.5.These impacts are addressed on a localized rather than regional basis and are specific to the sensitive receptors identified for the proposed project.Sensitive receptors are groups of individuals, including children, the elderly, the acutely ill, and the chronically ill, that may be more susceptible to health risks dueto chemical exposure,and sensitive-receptor population groups are likely to be located at hospitals, medical clinics, schools, playgrounds, childcare centers, residences, and retirement homes(BAAQMD 2017a).The closest existing sensitive receptors are receptors associated with the single-family residences located to the south on Castlewood Drive, both within approximately 320 feet of the trail alignment. "Incremental cancer risk" is the net increased likelihood that a person continuously exposed to concentrations of TACs resulting from a project over a 9-, 30-,and 70-year exposure period would contract cancer based on the use of standard Office of Environmental Health Hazard Assessment (OEHHA) risk-assessment methodology.(OEHHA 2015). In addition, some TACs have non- carcinogenic effects.TACs that would potentially be emitted during construction activities would be diesel particulate matter, emitted from heavy-duty construction equipment and heavy-duty trucks. Heavy-duty construction equipment and diesel trucks are subject to CARIB air toxic control measures to reduce diesel particulate matter emissions. According to the OEHHA, health risk assessments, which determine the exposure of sensitive receptors to toxic emissions, should be based on a 30-year exposure period for the maximally exposed individual resident; however,such assessments should be limited to the period/duration of activities associated with the project (OEHHA 2015). Thus, the duration of proposed construction activities (approximately 3-months) would only constitute a very small percentage of the total 30-year exposure period. Regarding long-term operations, the project would develop a mountain bike trail which would not result in any longterm air quality impacts. The project would not include any stationary sources that would emit air pollutants or TACs. In summary, the project would not expose sensitive receptors to substantial, longterm pollutant concentrations or health risk during construction or operations,and this impact would be less than significant for the project as well as the cumulative condition. 12956 DUDEK 25 April 2022