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5.1 AIR QUALITY
<br /> indicated in the figures,winds in California generally are light and easterly in the winter,but
<br /> strong and westerly in the spring,summer, and fall.
<br /> Wind speed and wind direction data have been recorded at the meteorological monitoring
<br /> station at the Stockton Metropolitan Airport. This station is located approximately 16 miles to
<br /> the south-southeast, and is considered representative of meteorological conditions in the
<br /> project area. Quarterly wind roses and wind frequency distribution tables are provided in
<br /> Appendix 5.1B. Wind patterns at the project site can be seen in Appendix 5.113,
<br /> Figures 5.1B-2A through 5.113-6E,which show quarterly and annual wind roses for
<br /> meteorological data collected at the Stockton Metropolitan Airport meteorological station
<br /> during 2000 through 2004. The annual wind rose for 2004 is typical for this location and is
<br /> shown as Figure 5.1-1. It can be seen that the winds are mild (12.8 percent calm conditions)
<br /> and predominantly from the northwestern quadrant. On an annual basis,approximately
<br /> 57.6 percent of the winds come from the west through north-northwest.Winds are
<br /> predominantly from the northwest and southeast during the first quarter,from the west
<br /> during the second quarter,from the northwest during the third quarter,and from the
<br /> southeast during the fourth quarter. Southeasterly winds develop mainly during the first and
<br /> fourth quarters and are essentially absent during the other quarters.
<br /> The mixing heights of the area are affected by the eastern Pacific high-pressure system and
<br /> marine influences. Often,the base of the inversion is found at the top of a layer of marine air,
<br /> because of the cooler nature of the marine environment. Smith,et al, (1984) reported that at
<br /> Oakland, the nearest upper-level meteorological station(located approximately 50 miles
<br /> west-southwest of the project site),50th percentile morning mixing heights for the period
<br /> 1979-80 were on the order of 1,770 feet (530 to 550 meters) in summer and fall, and 3,600 to
<br /> 3,900 feet (1,100 to 1,200 meters) in winter and spring. The 50th percentile afternoon mixing
<br /> heights ranged from 2,150 and 3,030 feet (660 to 925 meters) in summer and fall, and over
<br /> 3,900 feet (over 1200 meters) in winter and spring.Such mixing heights provide generally
<br /> favorable conditions for the dispersion of pollutants. Inland areas,where the marine
<br /> influence is weaker, often experience strong ground-based inversions during cold weather
<br /> periods.These inversions inhibit dispersion of low-lying sources of air pollution, such as
<br /> cars,trucks and buses, and can result in high pollutant concentrations.
<br /> 5.1.1.3 Criteria Pollutants and Air Quality Trends
<br /> 5.1.1.3.1 State and National Air Quality Standards
<br /> The U.S. Environmental Protection Agency (EPA) has established national ambient air
<br /> quality standards (NAAQS) for ozone,nitrogen dioxide (NO2), carbon monoxide (CO), sulfur
<br /> dioxide (SO2),particulate matter with aerodynamic diameter less than or equal to 10 microns
<br /> (PM1o),particulate matter with aerodynamic diameter less than or equal to 2.5 microns
<br /> (PM2.5),and airborne lead. In addition,the California Air Resources Board (CARB) has
<br /> established standards for ozone, CO,NO2,SO2, sulfates,PM1o, airborne lead,hydrogen
<br /> sulfide, and vinyl chloride at levels designed to protect the most sensitive members of the
<br /> population,particularly children,the elderly, and people who suffer from lung or heart
<br /> diseases. Areas with air pollution levels above these standards can be considered
<br /> "nonattainment areas" subject to planning and pollution control requirements that are more
<br /> stringent than standard requirements. The attainment status of the San Joaquin Valley air
<br /> basin with respect to federal and state standards is summarized in Table 5.1-1.
<br /> SAC/371322/082410013(LEC_5.1_AIR_QUALITY.DOC) 5.1-3
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