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4.5 AIR QUALITY <br /> Ozone <br /> Ozone is the most prevalent of a class of photochemical oxidants formed in the urban atmosphere. The <br /> creation of ozone is a result of complex chemical reactions between hydrocarbons and oxides of <br /> nitrogen in the presence of sunlight. Unlike other pollutants, ozone is not released directly into the <br /> atmosphere from any sources. The major sources of oxides of nitrogen and hydrocarbons, known as <br /> ozone precursors, are combustion sources such as factories and automobiles, and evaporation of solvents <br /> and fuels. The health effects of ozone are eye irritation and damage to lung tissues. Ozone also <br /> damages some materials, such as rubber, plants, and crops (Stern, 1977). <br /> Ozone is the air pollutant that causes the most damage to agricultural crops in California. The most <br /> significant crop losses in California from ozone occur in the San Joaquin Valley (Thompson and Olszyk, <br /> 1988). <br /> Suspended Particulate Matter (PM-10) <br /> Suspended particulate matter consists of solid and liquid particles of dust, soot, aerosols and other <br /> matter, small enough to remain suspended in the air for a long period of time. A portion of the <br /> suspended particulate matter in the air is from natural sources such as wind blown dust and pollen. <br /> Man-made sources include combustion, automobiles, field burning, factories, and unpaved roads. <br /> Particulate matter also results from photochemical reactions in the atmosphere. <br /> The effects of high concentrations of suspended particulate matter on humans include aggravation of <br /> chronic disease and heart/lung disease symptoms. Non-health effects include reduced visibility and <br /> soiling of surfaces (Stern, 1977). <br /> Carbon Monoxide <br /> Carbon monoxide is an odorless, colorless gas that is highly toxic. It is formed by the incomplete <br /> combustion of fuels, and its main source in San Joaquin County is automobiles. Carbon monoxide's <br /> health effects are related to its affinity for hemoglobin in the blood. At high concentrations, carbon <br /> monoxide reduces the amount of oxygen in the blood, causing heart difficulties in people with chronic <br /> diseases, reduced lung capacity, and impaired mental abilities (Stern, 1977). <br /> Regional Air Quality Planning <br /> Federal Program <br /> The U.S. Clean Air Act Amendments of 1977 required that each state identify areas within its borders <br /> that do not meet federal primary standards as non-attainment areas. The states were required to prepare <br /> a State Implementation Plan (SIP) to show how the federal standards were to be attained by 1987. <br /> However, the federal ambient air quality standards were not met in San Joaquin County by 1987. <br /> 4.5-3 <br />