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7.B. - Page 78 Redwood City Chapter 4.Environmental Impact Analysis center,the ambient short-term air pollutant concentrations were modeled for onsite employees and customers and offsite residents.The analysis used the most recent vehicle emission rates for San Mateo County,which are 40 to 75 percent lower than the vehicle emission rates used in the 2007 FEIR.The current vehicle emission rates reflect cleaner later model year vehicles that incorporate current emission controls and fewer older vehicles with higher emission rates.As shown in Table 4.4-7,the ambient short-term CO3 NOa,and PM10 concentrations would increase by less than 1 percent of the relevant CAAQS for onsite employees and customers,and would increase by less than 0.5 percent of the relevant CAAQS for offsite residents.Therefore,new ambient air quality impacts associated with vehicle queuing at the 20-station fueling center would be less than significant. Table 4.4-7.Air Pollutant Exposure Due To Vehicle Idling, Original Project Plus Proposed Modification Concentration(µg/m3') Receptor 1-hour NOZ 1-hour CO 8-hour CO 24-hour PM10 Modeled Employee Exposure 0.71 79.8 55.9 0.09 Percent of Standard 0.38% 0.35% 0.56% 0.18% Modeled Resident Exposure 0.31 34.1 23.9 0.04 Percent of Standard 0.16% 0.15% 0.24% 0.08% Concentration Thresholds 188 23,000 10,000 50 Exceed Threshold? No No No No Source:Ashworth Leininger Group 2012 (Appendix C of ALG report,Table G1a). Notes: *µg/m3=micrograms per cubic meter. c. Result in a cumulatively considerable net increase of any criteria pollutant for which the project region is non-attainment under an applicable federal or state ambient air quality standard(including releasing emissions which exceed quantitative thresholds for ozone precursors)? Less-than-Significant New Impact.The BAAQMD considers air pollution associated with criteria pollutants to be largely a cumulative impact.As such,the BAAQMD has established emissions thresholds which it believes a project's individual operational criteria pollutant emissions would be cumulatively considerable.Therefore,it considers the project-level criteria pollutant thresholds to address both project-level and cumulative impacts (Bay Area Air Quality Management District California Environmental Quality Act Air Quality Guidelines,Updated May 2011,page 2-1). As discussed in Section 4.4.b,the construction and operation emissions associated with the project plus proposed modifications were estimated to be well below the significant thresholds;therefore, the project plus proposed modifications,in combination with other projects in the area,would not result in a significant cumulative impact on air quality. d. Expose sensitive receptors to substantial pollutant concentrations? Construction Fugitive Dust Less-than-Significant New Impact with Mitigation Incorporated. During grading and excavation activities,dust would be generated.The amount of dust generated would be highly variable and is dependent on the size of the disturbed area at any given time,amount of activity,soil conditions,and Addendum No.2 to the Environmental Impact Report for 4-33 September 2012 the Redwood City Costco Wholesale Project ICF 00154.12