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d San Joaquin County Community Environmental Setting, Impacts,and Mitigation Measures Development Department Air Quality r while the federal 8-hour standard is 0.08 ppm,not to be exceeded more than three times in any 3-year period. The state has established a 1-hour ozone standard of 0.09 ppm,not to be exceeded, while the federal 1-hour ozone standard of 0.12 ppm has recently been replaced by the 8-hour standard described above. State and federal standards are summarized in Table 3.0-1. ` Carbon Monoxide. CO is essentially inert to plants and materials but can have significant effects on human health. CO is a public health concern because it combines readily with hemoglobin and thus reduces the amount of oxygen y transported in the bloodstream. Effects on humans range from slight headaches to nausea to death. Motor vehicles are the dominant source of CO emissions in most areas. High CO levels develop primarily during winter when periods of light winds combine with the formation of ground level temperature inversions(typically from the evening �r through early morning). These conditions result in reduced dispersion of vehicle emissions. Motor vehicles also exhibit increased CO emission rates at low air temperatures. L State and federal CO standards have been set for both 1-hour and 8-hour averaging times. The state 1-hour standard is 20 ppm by volume,and the federal y 1-hour standard is 35 ppm. Both state and federal standards are 9 ppm for the 8- hour averaging period. State and federal standards are summarized in Table 3.C- 1. ` Inhalable Particulate Matter. Particulates can damage human health and retard plant growth. Health concerns associated with suspended particulate matter p focus on those particles small enough to reach the lungs when inhaled. L Particulates also reduce visibility and corrode materials. The federal and state ambient air quality standard for particulate matter applies to two classes of particulates: particulate matter 10 microns or less in diameter (PM 10) and particulate matter 2.5 microns or less in diameter(PM2.5). The state PM10 standards are 50 micrograms per cubic meter(1A/m3)as a 24-how average L, and 20 µ/m3 as an annual geometric mean. The federal PM 10 standards are 150 µ/m3 as a 24-hour average and 50 µ/m3 as an annual arithmetic mean. The federal PM2.5 standards are 15 µ/m3 for the annual average and 65 µ/m3 for the ` 24-hour average. The state PM2.5 standard is 12 µ/m3 as an annual geometric mean. State and federal standards are summarized in Table 3.0-1. Toxic Air Contaminants. Toxic air contaminants(TACs)are pollutants that may be expected to result in an increase in mortality or serious illness or that may pose a current or potential hazard to human health. Health effects of TACs include cancer,birth defects,neurological damage,damage to the body's natural defense system, and diseases that lead to death. ARB has identified diesel exhaust particulate matter as a TAC. DeSilva Gates Quarry Project Draft Environmental Impact Report 3.C-3 JSS 05105.05