A comparison of ozone exposure in Fresno and Shaver Lake, California.* Ozone is formed by a chemical reaction between nitrogen oxides and volatile organic compounds volatile organic compound Environment Any toxic cabon-based (organic) substance that easily become vapors or gases–eg, solvents–paint thinners, lacquer thinner, degreasers, dry cleaning fluids in the presence of sunlight. * The availability of nitric oxide nitric oxide or nitrogen monoxide, a colorless gas formed by the combustion of nitrogen and oxygen as given by the reaction: energy + N2 + O2 → 2NO; m.p. −163.6°C;; b.p. −151.8°C;. and nitrogen dioxide downwind of a source area controls the concentrations of ozone that can be formed photochemically. * The intensity and the distribution of ozone formation are controlled by the properties of the available hydrocarbons. * Ozone is a powerful oxidant oxidant /ox·i·dant/ (ok´si-dant) the electron acceptor in an oxidation-reduction (redox) reaction. ox·i·dant n. See oxidizer. . * It is toxic to animals, can cause crop damage, and can cause visible injury to plant leaves and needles. * In humans, the effects of ozone on the upper respiratory system respiratory system: see respiration. respiratory system Organ system involved in respiration. In humans, the diaphragm and, to a lesser extent, the muscles between the ribs generate a pumping action, moving air in and out of the lungs through a include coughing, throat irritation, and difficulty breathing. * Even at relatively low levels, ozone may cause inflammation and irritation of the respiratory tract respiratory tract n. The air passages from the nose to the pulmonary alveoli, including the pharynx, larynx, trachea, and bronchi. Respiratory tract , particularly during physical activity. * Ozone worsens asthma attacks. * It can increase the susceptibility of the lungs to infections, allergens, and other pollutants. * It may aggravate chronic lung diseases such as emphysema emphysema (ĕmfĭsē`mə), pathological or physiological enlargement or overdistention of the air sacs of the lungs. A major cause of pulmonary insufficiency in chronic cigarette smokers, emphysema is a progressive disease that commonly and bronchitis. * It may reduce the ability of the immune system immune system Cells, cell products, organs, and structures of the body involved in the detection and destruction of foreign invaders, such as bacteria, viruses, and cancer cells. Immunity is based on the system's ability to launch a defense against such invaders. to fight bacterial infection in the respiratory system. * Ozone and its precursors may be transported over distances of hundreds of kilometers. Ozone formation and accumulation occur over time scales of several hours. * As a result, the highest ozone concentrations occur downwind of urban locations. * But the majority of pollution monitoring takes place at lower elevations and mostly in urban areas. * Few studies have measured ozone exposure in mountainous regions downwind from highly polluted urban centers, * Many people have misconceptions about the air quality in the mountains. * They may think that when visiting the mountains during the summer months they are breathing clean air. * Total ozone exposure in mountainous areas, however, can be considerably higher than in valley sites. * The study reported here evaluated ozone levels in Fresno, California, and the downwind community of Shaver Lake, California Shaver Lake is a census-designated place (CDP) in Fresno County, California, United States. The population was 705 at the 2000 census. Geography According to the United States Census Bureau, the CDP has a total area of 89.8 km² (34.7 mi²). 83.8 km² (32. . * Fresno is in the San Joaquin Valley Noun 1. San Joaquin Valley - a vast valley in central California known for its rich farmland Calif., California, Golden State, CA - a state in the western United States on the Pacific; the 3rd largest state; known for earthquakes , which has ozone levels that are among the highest recorded in the country. * The results of the study reported here indicate that Shaver Lake, a rural area, experiences higher 24-hour-average ozone contamination than does its urban counterpart Fresno. * The difference results from ozone levels remaining higher in the mountains during the night. * Other studies have found that ozone levels in mountainous sites do not deplete de·plete v. 1. To use up something, such as a nutrient. 2. To empty something out, as the body of electrolytes. rapidly. Thus the total ozone exposure in mountainous areas can be considerably higher than the total exposure in valley sites. * Several actions might be considered to address high ozone levels in the Sierra Nevada National Forest: -- Issue health advisories for ozone levels occurring in Shaver Lake. -- Educate and encourage the public to support hybrid-electric vehicles, to demand that new transportation technologies be developed as soon as possible, and to avoid or reduce activities that cause air pollution. -- Motivate the public to place pressure on local, state, and federal governments to support research that can be used to update health and environmental guidelines. |
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