SU0014565 (2) - Laserfiche WebLink

Home Browse Search

3.6 AIR QUALITY EXISTING SETTING Project Site. The project area is located south of Tracy about 25 miles south/ southwest of Stockton and 35 miles west/northwest of Modesto. The prevailing wind flows are from the west to northwest. Air pollutants from the Tracy area are transported to southern San Joaquin County and the Modesto area in Stanislaus County. The project is within the San Joaquin County Air Pollution Control District (SJCAPCD). San Joaquin County is the northernmost of the eight counties in the San Joaquin Valley Air Basin. This basin has the potential of creating serious air pollution problems because the meteorology and topography often allow air pollutants to concentrate. San Joaquin County's air quality problems occur during the late spring through early winter period. From May to October high ozone levels are a recurring problem. Intense heat and sunlight are available to react with hydrocarbons and nitrogen oxides to form ozone. From early fall through early winter (October through January) strong temperature inversions can trap pollutants near the earth's surface for weeks at a time. During these periods carbon monoxide levels will steadily build up and often reach or exceed the Federal and State eight hour standards. Visibility reducing particulates are a problem much of the year in the air basin. Dust from a variety of agricultural operations is a chief contributor to this problem. Attainment Status. The entire San Joaquin County Air Pollution Control District is currently nonattainment for ozone (03) and total suspended particulates (TSP), and Stockton is nonattainment for carbon monoxide (CO) (San Joaquin County 1982 Air Quality Management Plan). As a nonattainment region, the region must participate in the State Implementation Plan pursuant to the Clean Air Act and amendments thereto. The San Joaquin County 1982 Air Quality Management Plan developed strategies to attain Federal standards for 03 and CO by the end of 1987. The ARB prepared the State's TSP nonattainment plan for the 1982 State Implementation Plan (SIP) revision. Nature and Source of Pollutants. National primary and secondary ambient air quality standards have been established by the U.S. Environmental Protection Agency to protect the public health (primary) and welfare (secondary). The California Air Resources Board (CARB) has established similar air quality standards. Table 1 of Appendix 13.4 presents Federal and California air quality standards. Air Quality Record. Table 3.6-1 summarizes the number of days air quality standards were exceeded in San Joaquin and Stanislaus Counties during the three year period 1983 to 1985. Nitrogen dioxide and sulfur dioxide never exceeded the air quality standards during these years. The standards were exceeded for ozone, carbon monoxide and total suspended particulates. 3.6-1