Table 515 Effects Attributed To Sulfur Dioxide

Category of Effect Comments

Health a. At concentrations of about 1500 fg/m3 (0.52 ppm) of sulfur dioxide (24-hr average) and sus pended particulate matter measured as a soiling index of 6 cohs or greater, mortality can increase.

b. At concentrations of about 715 fg/m3 (0.25 ppm) of sulfur dioxide and higher (24-hr mean), accompanied by smoke at a concentration of 750 fg/m3, the daily death rate can increase.

c. At concentrations of about 500 fg/m3 (0.19 ppm) of sulfur dioxide (24-hr mean), with low particulate levels, mortality rates can increase.

d. At concentrations ranging from 300 to 500 fg/m3 (0.11 to 0.19 ppm) of sulfur dioxide (24-hr mean) with low particulate levels, increase hospital admissions of older people for respiratory disease can increase; absenteeism from work, particularly with older people, can also occur.

e. At concentrations of about 715 fg/m3 (0.25 ppm) of sulfur dioxide (24-hr mean) accompanied by particulate matter, illness rates for patients over age 54 with severe bronchitis can rise sharply.

f. At concentrations of about 600 fg/m3 (about 0.21 ppm) of sulfur dioxide (24-hr mean) with smoke concentrations of about 300 fg/m3, patients with chronic lung disease can experience accentuation of symptoms.

g. At concentrations ranging from 105 to 265 fg/m3 (0.037 to 0.092 ppm) of sulfur dioxide (annual mean) accompanied by smoke concentrations of about 185 fg/m3, the frequency of respiratory symptoms and lung disease can increase.

h. At concentrations of about 120 fg/m3 (0.046 ppm) of sulfur dioxide (annual mean) accompanied by smoke concentrations of about 100 fg/m3, the frequency and severity of respiratory diseases in school children can increase.

i. At concentrations of about 115 fg/m3 (0.040 ppm) of sulfur dioxide (annual mean) accompanied by smoke concentrations of about 160 fg/m3, mortality from bronchitis and lung cancer can increase.

Visibility At a concentration of 285 fg/m3 (0.10 ppm) of sulfur dioxide with a comparable concentration of particulate matter and relative humidity of 50%, visibility can be reduced to about 5 mi.

Materials At a mean sulfur dioxide level of 345 fg/m3 (0.12 ppm) accompanied by high particulate levels, the corrosion rate for steel panels can increase by 50%.

Vegetation a. At a concentration of about 85 fg/m3 (0.03 ppm) of sulfur dioxide (annual mean), chronic plant injury and excessive leaf drop can occur.

b. After exposure to about 860 fg/m3 (0.3 ppm) of sulfur dioxide for 8 hr, some species of trees and shrubs show injury.

c. At concentrations of about 145 to 715 fg/m3 (0.05 to 0.25 ppm), sulfur dioxide can react synergistically with either ozone or nitrogen dioxide in short-term exposures (e.g., 4 hr) to produce moderate to severe injury to sensitive plants.

Source: National Air Pollution Control Administration, 1969, Air quality criteria for sulfur oxides, Pub. No. AP-50 (Washington, D.C. [January]: 161-162).

week time period. Other episodes occurred recently in locations throughout the United States, and others are anticipated in subsequent years. Generally, the individuals most affected by these episodes are older people already experiencing difficulties with their respiratory systems. Common characteristics of these episodes include pollutant releases from many sources, including industry, and limiting atmospheric dispersion conditions.

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