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Administrative Draft Environmental Impact Report Gill Medical Center Project 4.5.3 Environmental Impacts and Mitigation Measures 4.5.3.1 Thresholds of Significance According to Appendix G of the CEQA Guidelines, air quality impacts are considered significant if implementation of the Proposed Project would: Conflict with or obstruct implementation of an applicable air quality plan; Result in a cumulatively considerable net increase of any criteria pollutant for which the Project region is nonattainment under an applicable federal or state ambient air quality standard (including releasing emissions which exceed quantitative thresholds for ozone precursors); Expose sensitive receptors to substantial pollutant concentrations; Result in other emissions (such as those leading to odors adversely affecting a substantial number of people). 4.5.3.2 Methods of Analysis Air quality impacts were assessed in accordance with methodologies recommended by CARB and the SJVAPCD. Onsite construction (including worker commutes and vendors), operational area source, and energy source emissions were modeled using the California Emissions Estimator Model (CalEEMod), version 2016.3.2. CalEEMod is a statewide land use emissions computer model designed to quantify potential criteria pollutant emissions associated with both construction and operations from a variety of land use projects. Operational mobile source emissions are calculated with the 2017 version of the EMission FACtor model (EMFAC) developed by CARB. EMFAC 2017 is a mathematical model that was developed to calculate emission rates from motor vehicles that operate on highways, freeways, and local roads in California and is commonly used by CARB to estimate changes in future emissions from on-road mobile sources. The most recent version of this model, EMFAC 2017, incorporates regional motor vehicle data, information and estimates regarding the distribution of vehicle miles traveled by speed, and number of starts per day. The most important improvement in EMFAC 2017 is the integration of the new data and methods to estimate emissions from diesel trucks and buses. The model includes the emissions benefits of the truck and bus rule and the previously adopted rules for other on-road diesel equipment. As previously described, Phase 1 construction is anticipated to begin in late 2021 and take approximately 12 months to complete. The Phase 1 Medical Center Building is expected to begin operations in 2023. Phase 2 construction is scheduled to begin in 2029 and take approximately 20 months to complete.The Phase 2 Hospital and other support uses are expected to begin operation in 2031. Project construction- generated air pollutant emissions were calculated based on this timeline and the expected construction equipment provided by the Project applicant and identified in Section 3.0, Project Description. Operational air pollutant emissions are based on the Project site plans and the estimated traffic trip generation rates and Project fleet mix from KD Anderson and Associates (2020). Helicopter emissions are calculated based on the emission factors identified for a UH-1 N with two T400-CP-400 engines contained in the Air Force 2020 Mobile Emissions Calculations Guide (Air Force Civil Engineer Center 2020). The UH- Air Quality 4.5-12 October 2021