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CHAPTER 10.0 AIR QUALITY A. ENVIRONMENTAL SETTING 1. Air Pollution Climatology The project site is located within the San Joaquin Valley air basin. This air basin is a well-defined climatic region, primarily because of the topographic barriers forming distinct boundaries on three sides of the basin. The western boundary is formed by the Coast Range, the southern boundary by the Tehachapi Mountains, and the eastern boundary by the Sierra Nevada. Only the northern oundary is not marked by a distinct topographic feature. In the northern portion of the basin, the Carquinez Strait, a sea level lap between the Coast Ranges,extends to the west and is a major source of ventilationor the basin. Winds measured at Stockton show a strong dominance of west to northwesterly winds. (California Department of Water Resources, 1978) Wind speeds are generally highest during the spring months and lightest in the fall and winter. The general windflow in the rest of the San Joaquin Valley is northwesterly most of the year, carrying pollutants from the northern portion of the valley towards the south. This general flow also transports pollutants from the Bay Area into the air basin. 2. Air pollutants and AmbientStandards The Mulford-Carrel Act of 1969 and the Clean Air Act Amendments of 1970 established state and federal air quality standards for several pollutants. These standards are divided into primary standards, designed to protect the public health, and secondary standards, intended to protect the public welfare from effects such as visibility reduction, soiling, nuisance and other forms of damage. The state and federal standards are summarized in Table 10-1. 3. Sensitive Receptors Sensitive receptors for air quality include land uses such as residences, hospitals and convalescent homes. There are scattered residences located along Lovelace Road near the project site,but none are located directly adjacent to the site. 4. Current Air Quality The California Air Resources Board maintains three air quality monitorin& sites within the Stockton area. A summary of air quality data from these monitoring sates is shown in Table 10-2 for the years 1987-1991. Table 10-2 shows that the standards for ozone,carbon monoxide andarticulate matter (PM-10) are exceeded in the Stockton area. Levels of sulfur dioxide and nitrogen dioxide do not exceed either the state or federal standards. 10-1