ARCHIVED REPORTS_DRAFT ENVIRONMENTAL IMPACT REPORT

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Emissions of ozone precursors ROG and NOx have decreased over the past several years because of more stringent motor vehicle standards and cleaner burning fuels. The ozone problem in the SJVAB ranks among the most severe in the state. Peak levels have not declined as much as the number of days that standards are exceeded has declined. From 1985 to 2004,the maximum peak 8-hour indicator decreased by only 2%. The number of days when the national 8-hour standard has been exceeded has been quite variable over the years. This variability has resulted in part from the influence of meteorology as well as changes to the monitoring network. The monitoring network was not as extensive during the 1980s as it has been during the last 14 years. For this reason,the period of 1990-2005 provides a better indication of trends. During this period,there was an 8%decrease in the 3-year average of the number of exceedance days of the national 8-hour standard(ARB 2006a). Carbon Monoxide CO is a colorless, odorless, and poisonous gas produced by incomplete burning of carbon in fuels,primarily from mobile (transportation) sources. In fact, 77% of the nationwide CO emissions are from mobile sources. The other 23%consists of CO emissions from wood-burning stoves, incinerators, and industrial sources. CO enters the bloodstream through the lungs by combining with hemoglobin,which normally supplies oxygen to the cells. However, CO combines with hemoglobin much more readily than oxygen does,resulting in a drastic reduction in the amount of oxygen available to the cells. Adverse health effects associated with exposure to CO concentrations include such symptoms as dizziness,headaches, and fatigue. CO exposure is especially harmful to individuals who suffer from cardiovascular and respiratory diseases (EPA 2006a). The highest concentrations are generally associated with cold, stagnant weather conditions that occur during the winter. In contrast to problems caused by ozone,which tends to be a regional pollutant, CO problems tend to be localized. Nitrogen Dioxide NO2 is a brownish,highly reactive gas that is present in all urban environments. The major human-made sources of NO2 are combustion devices, such as boilers,gas turbines, and mobile and stationary reciprocating internal combustion engines. Combustion devices emit primarily nitric oxide(NO),which reacts through oxidation in the atmosphere to form NO2(EPA 2006a). The combined emissions of NO and NO2 are referred to as NOx and reported as equivalent NO2. Because NO2 is formed and depleted by reactions associated with photochemical smog(ozone),the NO2 concentration in a particular geographical area may not be representative of the local NOx emission sources. Inhalation is the most common route of exposure to NO2.Because NO2 has relatively low solubility in water,the principal site of toxicity is in the lower respiratory tract. The severity of the adverse health effects depends primarily on the concentration inhaled rather than the duration of exposure.An individual may experience a variety of acute symptoms,including coughing,difficulty with breathing,vomiting,headache,and eye irritation during or shortly after exposure.After a period of approximately 4-12 hours,an exposed individual may experience chemical pneumonitis or pulmonary edema with breathing abnormalities,cough,cyanosis,chest pain,and rapid heartbeat. Severe, symptomatic NO2 intoxication after acute exposure has been linked on occasion with prolonged respiratory impairment with such symptoms as chronic bronchitis and decreased lung functions(EPA 2006a). Sulfur Dioxide SO2 is produced by such stationary sources as coal and oil combustion, steel mills,refineries, and pulp and paper mills. The major adverse health effects associated with SO2 exposure pertain to the upper respiratory tract. SO2 is a respiratory irritant with constriction of the bronchioles occurring with inhalation of SO2 at 5 ppm or more. On contact with the moist mucous membranes, SO2 produces sulfurous acid,which is a direct irritant. Concentration EDAW Manteca WQCF and Collection System Master Plans EIR Air Quality 4.3-4 City of Manteca