A sampling and analytical method for determining the epoxide content of aerosols of epoxy resins and curing agents was summarized. The method consisted of collecting aerosol samples in a midget impinger containing 10 milliliters dimethylformamide, which inhibited the epoxy curing reaction. The samples were reacted with bromide in perchloric-acid in a ratio of epoxide/bromide/perchloric-acid of 1:3:10 for 4 hours at 22 to 24 degrees. The amount of bromide reacted corresponded to the amount of epoxide in the sample. The amount of bromide remaining in the sample was determined by normal pulse polarography. The method could determine samples containing 1 to 100 microequivalents (microeq) of epoxide functionality. When used to analyze reference samples containing 7.41, 14.4, or 23.7mg/m3 epoxide, the measured concentrations were 6.65, 13.6, and 23.0mg/m3. The corresponding standard deviations were 0.049, 0.264, and 0.860mg/m3 and coefficients of variation were 0.007, 0.019, and of aerosols in industrial paint spraying operations using epoxy paints. In tank painting with a high solids spray the mean aerosol concentration was 3.11mg/m3 and the epoxide concentration was 5.20 microequivalents (microeq). In ceiling painting with a high solids spray paint, the mean aerosol concentration was 18.5mg/m3 and the epoxide concentration was 9.16microeq. In aircraft painting with a low solids paint the mean aerosol concentration was 5.73mg/m3. No epoxide was detected. The authors conclude that an analytical method for a contaminant can be based on its reactive properties. Spray painting with epoxy containing paints can produce exposures to reactive epoxy functional groups.