Biologic Effects of Nitrogen Dioxide in Relation to Air Quality Standards

Data on the biologic effects of nitrogen dioxide on man and lower animals over a wide range of concentrations has been reviewed and tabulated. Present evidence suggests that long-continued exposures should not exceed the range 0.5-1 ppm. This is based on the evidence of increased mortality in lower animals exposed to aerosolized microorganisms after NO/sub 2/ exposures and the pathologic effects demonstrable in animals continuously exposed to levels in the range of 4-5 ppm. Brief exposures of a general population should not exceed 3 ppm over a period of one hour. This is based on the possible potentiation of infections and on the odor threshold. The above recommendations relate to the possible effects of NO/sub 2/ on health alone. They do not consider potentiation or additive effects nor any contributions to plant damage and visibility. 55 references, 1 table.