The acid-insoluble dust (soot) contents of 146 male lung samples obtained at autopsy were measured. The mean content was 1.2 mgg −1 giving an estimated mean total soot accumulation for both lungs of 1.7 g. A statistically significant trend was found between age and quantity of soot accumulated ( p < 0.05), but no associations emerged when occupational history and smoking habits were taken into account When necropsy diagnoses were considered, 13 patients dying with mention of a cerebrovascular accident had accumulated significantly greater quantities of lung soot than the rest ( p < 0.001).