Includes bibliographical references (p. R-1-R-10). "Accepted for publication in Environment International, Pergamon Press, circa April, 1985."

This work presents a quantitative assessment of nonsmokers' risk of lung cancer from passive smoking. The estimates given should be viewed as preliminary and subject to change as improved research becomes available. It is estimated that U.S. nonsmokers are exposed to from 0 to 14 milligrams of tobacco tar per day, and that the typical nonsmoker is exposed to 1.4 milligrams per day. A phonomenological exposure-response relationship is derived, yielding 5 lung cancer deaths per year per 100,000 persons exposed, per milligram daily tar exposure. This relationship yields lung cancer mortality rates and mortality ratios for a U.S. cohort which are consistent to within 5% with the results of both of the large prospective epidemiological studies of passive smoking and lung cancer in the U.S. and Japan. Aggregate expsure to ambient tobacco smoke is estimated to produce about 5000 lung cancer deaths per year in U.s> nonsmokers aged [greater than or equal to] 35 years, with an average loss of life expectacy of 17 « 9 years per fatality. The estimated loss of life expectancy for the most-exposed passive smokers appears to be about 3/4 of that reported for pipe smokers and 1/2 of that for cigar smokers. Mortality from passive smoking is estimated to be about two orders of magnituded higher than that estimated for carcinogens currently regulated as hazardous air pollutants under the federal Clean Air Act.