Air sampled from the breathing zone of chimney sweeps during "dirty work" and soot samples were analysed for polycyclic aromatic hydrocarbons (PAH). A total of 20 PAH were quantified by gas chromatography-mass spectrometry in 115 air samples and 18 soot samples. These included benzo(b)fluoranthene, benzo(a)pyrene (BaP), chrysene, dibenz(a,h)anthracene, and indeno (1,2,3-cd)pyrene, all of which are animal carcinogens. The summed atmospheric concentration of these compounds depended on the type of fuel used and averaged 2 27 yg/m3 for oil fuel. If a mixture of oil and solid fuel was used the concentration was 5 06 ug/m3; pure solid fuel heating yielded 5 08Mg/m3. The air concentrations of BaP were 0-36, 0-83, and 0-82 pg/M3 respectively. The soot samples recovered after using the three different fuel types were 10 50, 109-10, and 51-25 mg BaP/kg. The maximum total concentrations of the five carcinogenic PAH were 243-70, 691 06, and 213-94 mg/kg respectively. The time weighted, shift mean concentrations of 0-02 to 0-21 pg/M3 benzo(a)pyrene obtained on 11 days form the basis for the industrial medical estimation of risk.