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MOUNTAIN HOUSE NEIGHBORHOODS K AND L INITIAL STUDY 5,ENVIRONMENTAL CHECKLIST 3.AIR QUALITY AND GREENHOUSE GAs EMISSIONS would be localized and variable. However,with implementation of Regulation VIII _. 9 controls,construction impacts would be reduced to less-than-significant levels. Toxic Air Contaminants TACs . Construction of the proposed project would result in short-term diesel particulate matter(DPM)emissions,which are IACs, from on-site heavy-duty equipment. Project construction would generate DPM emissions from the use of off-road diesel equipment required for site grading and excavation, and other construction activities. The dose to which sensitive receptors are exposed is the primary factor used to determine health risk. Dose is a function of the concentration of a substance or substances in the environment and the extent of exposure that person has with the substance. Dose is positively correlated with time, meaning that a longer exposure period would result in a higher exposure level for the maximally exposed individual. Thus,the risks estimated for a maximally exposed individual are higher if a fixed exposure occurs over a longer period of time.According to the Office of Environmental Health Hazard Assessment(OEHHA), health risk assessments,which determine the exposure of sensitive receptors to toxic emissions, should be based on a 70-year exposure period; however, such assessments should be limited to the period/duration of activities associated with the project. Thus,the duration of the proposed construction activities(approximately 4.5 years)would only constitute approximately 6.4 percent of the total 70-year exposure period. In addition,there are no sensitive receptors in close proximity to the project construction activities. Because the use of mobilized equipment would be temporary and there are no sensitive receptors located immediately adjacent to areas where construction would occur for prolonged periods, DPM from construction activities would not be anticipated to result in the exposure of sensitive receptors to levels that exceed applicable standards. In addition,the long-term operation of the project would not result in any non- permitted sources of toxic air emissions.As a result,exposure of sensitive �.� receptors to substantial toxic air emissions from the project would be a less-than- significant impact. -'- e) Would the project create objectionable odors affecting a substantial number of people? Project development would occur near the existing wastewater treatment plant that could be a potential source of odors under certain operational and meteorological conditions. (As discussed in Section 5.9, Land Use and Planning, of this Initial Study,the wastewater treatment plant is located in the Old River Industrial Park near the southeast corner of Neighborhood L.) Objectionable odors are not anticipated at the project due to the prevailing wind direction. However,since project development would be within the SJVAPCD screening distance of 2 miles for wastewater treatment plants and because wind direction 541 f!