The category of health effects ranges from personal discomfort to actual health hazards. Personal discomfort is characterized by eye irritation and irritation to individuals with respiratory difficulties. Eye irritation is associated with oxidants and the components within the oxidant pool such as ozone, proxyacetylnitrate, and others. The burning sensation experienced routinely in many large urban areas is due to high oxidant concentrations. Individuals with respiratory difficulties associated with asthma, bronchitis, and sinusitis experience increased discomfort as a result of oxidants, nitrogen oxides, and particulates.
Health effects result from either acute or chronic exposures. Acute exposures result from accidental releases of pollutants or air pollution episodes. Episodes with documented illness or death are typically caused by persistent (three to six days) thermal inversions with poor atmospheric dispersion and high air pollutant concentrations (Godish 1991). Exposures to lower concentrations for extended periods of time have resulted in chronic respiratory and cardiovascular disease; alterations of body functions such as lung ventilation and oxygen transport; impairment of performance of work and athletic activities; sensory irritation of the eyes, nose, and throat; and aggravation of existing respiratory conditions such as asthma (Godish 1991).
An overview of ambient air quality indicates the potential health effects. Table 5.1.3 shows ambient air quality trends in major urban areas in the United States. The table uses the pollutants standard index (PSI) to depict trends for fifteen of the largest urban areas.
Table 5.1.4 summarizes the effects attributed to specific air pollutants. Many of these effects are described in previous examples, thus this table is a composite of the range of effects of these air pollutants. Table 5.1.5 contains information on the effects of sulfur dioxide. The effects are arranged in terms of health, visibility, materials, and veg-
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