Coal smoke and cigarette smoke.
D000397:Air Pollution / Q000517:prevention & control; D003031:Coal; D005380:Financing, Government; D006801:Humans; D008171:Lung Diseases / Q000517:prevention & control; D012906:Smoke / Q000517:prevention & control; D012907:Smoking; D014481:United States
D003031:Coal; D012906:Smoke