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ÐP <br />2 Health Impacts from Criteria Pollutants <br />Criteria air pollutants (CAPs) are defined as pollutants for which the federal and state governments have <br />established ambient air quality standards, or criteria, for outdoor concentrations to protect public <br />health. The federal and state standards have been set, with an adequate margin of safety, at levels <br />above which concentrations could be harmful to human health and welfare. These standards are <br />designed to protect the most sensitive people from illness or discomfort. Pollutants of concern include <br />ozone (O), nitrogen oxides (NO), carbon monoxide (CO), sulfur oxides (SO), particulate matter less <br />3xx <br />than 10 microns in diameter (PM), and particulate matter less than 2.5 microns in diameter (PM). <br />102.5 <br />The STR ban has the potential to increase emissions of these pollutants and their health impacts are <br />discussed in the following paragraphs. <br />Ozone <br />O is a colorless gas that is formed in the atmosphere when volatile organic compounds (VOCs), <br />3 <br />sometimes referred to as reactive organic gases (ROG), and oxides of nitrogen (NO) react in the <br />x <br />presence of ultraviolet sunlight. O is not a primary pollutant; it is a secondary pollutant formed by <br />3 <br />complex interactions of two pollutants directly emitted into the atmosphere. The primary sources of <br />VOCs and NO, the precursors of O, are automobile exhaust and industrial sources. Meteorology and <br />X3 <br />terrain play major roles in O formation, and ideal conditions occur during summer and early autumn on <br />3 <br />days with low wind speeds or stagnant air, warm temperatures, and cloudless skies. Short-term <br />exposures (lasting for a few hours) to O at levels typically observed in Southern California can result in <br />3 <br />breathing pattern changes, reduction of breathing capacity, increased susceptibility to infections, <br />inflammation of the lung tissue, and some immunological changes. <br />Nitrogen Oxides <br />Most NO, like O, is not directly emitted into the atmosphere but is formed by an atmospheric chemical <br />23 <br />reaction between nitric oxide (NO) and atmospheric oxygen. NO and NO are collectively referred to as <br />2 <br />NO and are major contributors to O formation. The primary sources of NO, the precursor to NO, <br />X32 <br />include automobile exhaust and industrial sources. High concentrations of NO can cause breathing <br />2 <br />difficulties and result in a brownish-red cast to the atmosphere, causing reduced visibility. There is some <br />indication of a relationship between NO and chronic pulmonary fibrosis, and some increase in bronchitis <br />2 <br />in children (2 and 3 years old) has also been observed at concentrations below 0.3 parts per million by <br />volume (ppm). <br />Carbon Monoxide <br />Carbon Monoxide (CO) is a colorless and odorless gas formed by the incomplete combustion of fossil <br />fuels. CO is emitted almost exclusively from motor vehicles, power plants, refineries, industrial boilers, <br />ships, aircraft, and trains. In urban areas, such as Santa Ana, automobile exhaust accounts for the <br />majority of CO emissions. CO is a non-reactive air pollutant that dissipates relatively quickly; therefore, <br />ambient CO concentrations generally follow the spatial and temporal distributions of vehicular traffic. CO <br />concentrations are influenced by local meteorological conditions, primarily wind speed, topography, and <br />atmospheric stability. CO from motor vehicle exhaust can become locally concentrated when surface- <br />based temperature inversions are combined with calm atmospheric conditions, a typical situation at <br />dusk in urban areas between November and February. The highest levels of CO typically occur during <br />the colder months of the year when inversion conditions, where a layer of warm air sits atop cool air, <br /> <br />2/14 <br /> <br /> <br />