An analysis was made of particulate matter isolated from autopsied human lungs of deceased residents of the Tokyo metropolitan area, to establish a data base of elemental and toxic materials accumulated in lungs. Upper left lung lobes from 108 persons with no history of lung disease were studied. Black powder residues separated from lung tissue were analyzed by scanning and transmission electron microscopy with energy dispersive x-ray analysis, neutron activation, elemental analysis, electron spin resonance and x-ray diffraction. Mutagenicity of black deposits was assessed by the Ames test. Primary pathological results were chronic bronchiolitis, emphysema and pavement epithelium metaplasia and were related to heavy cigarette smoking. There was a significant positive correlation of particulate deposition rate with age. Various elements of natural and artificial environmental origin were detected. A high level of chromium (7440473) was noted in tissue from a chromium worker exposed to hexavalent chromium. Average total carbon (7440440) content was 55 weight percent and did not differ between smokers and nonsmokers. Average elemental carbon content was 39 weight percent. Carbon free radicals were detected and attributed to smoking and soot. Mutagenicity tests revealed one sample positive for both Salmonella-typhimurium (TA-98) and (TA- 100), while three samples were positive for (TA-98) only. Alpha- quartz (14808607) was observed in 55 samples, and asbestos (1332214) fibers were observed in three of ten samples analyzed. The latter were identified as chrysotile (12001295) in one sample and tremolite (77536686) and crocidolite (12001284) in another. The author concludes that multiple factors, including cigarette smoking, contribute to pulmonary disease due to environmental substances. These results may be useful in determining factors involved in lung disease caused by deposited particles.