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City of Pleasanton—Hidden Canyon Residences and Preserve Draft EIR Air Quality FirstCarbon Solutions 3.2-1 https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480016/EIR/3 - Draft EIR/21480016 Sec03-02 Air Quality.docx 3.2 - Air Quality 3.2.1 - Introduction This section describes existing air quality conditions regionally and locally as well as the relevant regulatory framework. This section also evaluates the possible impacts related to air quality that could result from implementation of the proposed project. Information included in this section is based, in part, on project-specific air quality modeling results utilizing California Emissions Estimator Model (CalEEMod) Version 2022.1. Complete modeling output is provided in Appendix B. There were no public comments related to air quality received during the scoping period. 3.2.2 - Environmental Setting The Bay Area Air Quality Management District (BAAQMD) is the regional air quality agency for the San Francisco Bay Area Air Basin (SFBAAB). Air quality in this area is determined by such natural factors as meteorology, terrain, and temperature, in addition to the presence of existing air pollution sources and ambient conditions. These factors, along with applicable regulations aimed at reducing air pollution, are discussed below. Air Pollutant Emissions Although air pollution potential is strongly influenced by climate and topography, the air pollution that occurs in a location also depends on the amount of air pollutant emissions in the surrounding area or transported from more distance places. Air pollutant emissions generally are highest in areas that have high population densities, high motor vehicle use, and/or industrialization. These contaminants, created by photochemical processes in the atmosphere, such as ozone, may result in high concentrations many miles downwind from the sources of their precursor chemicals. San Francisco Bay Area Air Basin The project site is located within the San Francisco Bay Area Air Basin (SFBAAB). The SFBAAB consists of Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, and Santa Clara counties; the southwestern portion of Solano County; and the southern portion of Sonoma County. The Bay Area’s diverse climate and topography influences air quality and pollution dispersion across the region. The region predominantly experiences a Mediterranean climate, characterized by mild, wet winters and dry, warm summers. The Bay Area is known for its microclimates, where weather conditions can vary significantly over short distances due to the region's complex topography, including hills, valleys, and proximity to the ocean. Areas closer to the coast, such as San Francisco and parts of San Mateo County, are influenced by the Pacific Ocean. Strong coastal winds which help disperse pollutants, leading to generally better air quality in coastal areas. Inland areas experience warmer temperatures and less fog. During certain weather conditions, temperature inversions can trap pollutants close to the ground, leading to higher concentrations of air pollution, particularly in inland valleys. Overall, while the Bay Area generally enjoys good air quality, certain factors like vehicle emissions, industrial activities, and wildfires can lead to periods of poor air quality. Air quality varies across the