A variety of protocols and test methods have been developed to examine combustion product toxicity of building and furnishing materials. To promote comparisons of results among such tests, a standard method for quantifying exposure intensity as an estimate of dosage was developed. Smoke concentrations (C) were calculated from sample weight-loss data and integrated over the animal exposure time (t), such that Ct products were obtained in units of "mg/L · minutes." Application of the method was demonstrated by calculating Ct products from data reported in the literature for forty-five materials examined by the University of Pittsburg test (UPT) method.Smoke concentrations from individual materials tested in the UPT method were not constant and some materials produced smoke for only one third of the 30-minute exposure period. Some smoke exposures calculated using the proposed method were as low as one-fourth to one-sixth of that implied by the reported LC 50 (g) values. Expression of toxic potency in Ct units [L(Ct) 50's ] changed the relative ranking of some materials. Generically similar materials exhibited similar L(Ct) 50's . The range of L(Ct) 50's , especially for wood products, was found to be narrow when compared to that of pure gases and vapors.