14 ATTACHMENT 6 - Appendix A - E

Summary of 2018 Spotorno Ranch Air Quality Analysis March 22, 2021 Page 4 Impact AIR-2. Local Significant Threshold Analysis The estimation of the project’s local construction and operational emissions focuses on the emissions and their impacts that the project generates on the local area surrounding the project. The localized assessment was performed separately for construction and operation. Construction Project construction would require general site clearing and grading/earthwork activities during construction. Emissions from construction activities are generally short-term in duration, but may still cause adverse air quality impacts. The project would generate emissions from construction equipment exhaust, worker travel, and fugitive dust as PM10 and PM2.5. The BAAQMD does not recommend a numerical threshold for dust particulate matter missions, but rather uses Best Management Practices (BMPs) to control fugitive dust. If appropriate BMP emissions control measures are implemented, then fugitive dust emissions during construction are not considered significant. Since the project does not currently include any dust control measures, the fugitive dust control measures identified in the BAAQMD’s Guidelines must be included to reduce localized dust impacts to less than significant. MM AIR-2 requires the application of BMPs for fugitive dust control. Implementation of MM AIR-2 ensures implementation and enforcement of the BMPs and thereby reduces the project’s construction-generated fugitive dust impact to less than significant. Therefore, with mitigation, short-term construction impacts associated with violating an air quality standard or contributing substantially to an existing or projected air quality violation would be less than significant. Operation Localized high levels of CO (CO hotspot) are associated with traffic congestion and idling or slow-moving vehicles. The BAAQMD recommends a screening analysis to determine if a project has the potential to contribute to a CO hotspot. The screening criteria identify when site-specific CO dispersion modeling is not necessary. The project would result in a less than significant impact to air quality for local CO if one of the following screening criteria are met: • The project is consistent with an applicable congestion management program established by the county congestion management agency for designated roads or highways, regional transportation plan, and local congestion management agency plans; or • The project traffic would not increase traffic volumes at affected intersections to more than 44,000 vehicles per hour; or • The project traffic would not increase traffic volumes at affected intersections to more than 24,000 vehicles per hour where vertical and/or horizontal mixing is substantially limited (e.g., tunnel, parking garage, bridge underpass, natural or urban street canyon, below-grade roadway). The project meets at least one of the three screening criteria; therefore, the project would not result in a significant impact to air quality for local CO emissions.