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At ground level, ozone (O3) is formed by a series of reactions, under the influence of sunlight, involving volatile organic compounds (VOC) combining with a group of air pollutants known as nitrogen oxides (NOx). VOC and NOx are called ozone precursors. Volatile organic compounds are emitted by automobiles and various commercial and industrial sources. Nitrogen oxides are by-products of burning fuel in automobiles and heavy industries. Ozone is the main ingredient of smog. Ozone concentrations can vary from time of year and from year to year. Changing weather patterns (especially the number of hot, sunny days), periods of air stagnation, wind patterns and other factors contribute to ozone formation. Ozone injures vegetation, damages materials (rubber and fabrics) and affects the respiratory system. Repeated exposure to ozone pollution may cause permanent damage to the lungs. Short-term exposure to ozone can cause chest pains, nausea, throat irritation, congestion, shortness of breath, pain when inhaling deeply, wheezing and coughing. It can worsen bronchitis, heart disease, emphysema, and asthma, and reduce lung capacity. According to the American Lung Association, tests of healthy adults and children during exercise show that even brief exposure to ozone at the minimum air quality standard results in decreased lung function. Exposure at higher levels can cause decreased lung function that persists for several days following exposure. Long-term exposure of animals to moderate ozone levels produced changes in lung structure. According to the Environmental Protection Agency, millions of Americans live in areas where the national ozone health standards are exceeded. Ground-level ozone damages plant life and is
responsible for 500 million dollars in reduced
crop production in the United States each year.
The gas adversely affects forests and crops by
slowing growth and damaging plant cells. It
interferes with the ability of plants to produce
and store food, making them more susceptible to
disease, insects, other pollutants, and harsh
weather. Ground-level ozone damages the foliage
of trees and other plants, ruining the scenic
views of cities, national parks and forests, and
recreation areas.
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