Laserfiche WebLink
4.2 Air Quality <br />This section discusses the Specific Plan’s potential impacts to regional and local air quality. The <br />vehicle miles traveled (VMT) estimate used in emissions analysis are based on the Transportation <br />Impact Analysis prepared by Kittelson & Associates, dated September 2017. The traffic study is <br />included as Appendix D to this EIR. <br />4.2.1 Setting <br />a. Climate and Topography <br />The Specific Plan Area is located in the San Francisco Bay Area Air Basin (SFBAAB). Air quality in the <br />SFBAAB is affected by the emission sources located in the region, as well as by natural factors. <br />Atmospheric conditions such as wind speed and direction, air temperature gradients, and local and <br />regional topography influence air quality. The SFBAAB is affected by a Mediterranean climate of <br />warm, dry summers and cool, damp winters. Topographical features, the location of the Pacific high- <br />pressure system, and varying circulation patterns resulting from temperature gradients affect the <br />speed and direction of local winds. The winds play a major role in the dispersion of pollutants. <br />Strong winds can carry pollutants far from their source; a lack of wind will allow pollutants to <br />concentrate in an area (Life Science!, Inc. 2004). <br />Air dispersion also affects pollutant concentrations. As altitude increases, air temperature normally <br />decreases. Inversions occur when colder air becomes trapped below warmer air, restricting the air <br />masses’ ability to mix. Pollutants also become trapped, which promotes the production of <br />secondary pollutants. Subsidence inversions, which can occur during the summer in the SFBAAB, <br />result from high-pressure cells that cause the local air mass to sink, compress, and become warmer <br />than the air closer to the earth. Pollutants accumulate as this stagnating air mass remains in place <br />for one or more days (CDFG and USFWS 2004). <br />The Specific Plan Area is in the Northern Alameda and Western Contra Costa Counties climatological <br />sub region where marine air traveling through the Golden Gate is a dominant weather factor. The <br />Oakland-Berkeley Hills cause the westerly flow of air to split off the north and south of Oakland <br />causing diminishing wind speeds and temperatures averaging from the mid-50s to mid-70s degrees <br />Fahrenheit. The air pollution potential is lowest for the parts of the sub region closest to the bay and <br />air pollution in San Leandro is marginally higher because of the lower frequency of strong winds <br />(BAAQMD 2017). <br />b. Air Pollutants of Primary Concern <br />The Federal and State Clean Air Acts mandate the control and reduction of certain air pollutants. <br />Under these laws, the U.S. Environmental Protection Agency (U.S. EPA) and the California Air <br />Resources Board (CARB) have established ambient air quality standards for certain “criteria” <br />pollutants. Ambient air pollutant concentrations are affected by the rates and distributions of <br />corresponding air pollutant emissions, as well as by the climate and topographic influences <br />discussed above. The primary determinant of concentrations of non-reactive pollutants, such as <br />carbon monoxide (CO) and suspended particulate matter, is proximity to major sources. Ambient CO <br />levels usually closely follow the spatial and temporal distributions of vehicular traffic. A discussion of <br />primary criteria pollutants is provided below. <br />140