We need to know.
D000367:Age Factors; D000397:Air Pollution; D001991:Bronchitis / Q000453:epidemiology; D002908:Chronic Disease; D003644:Death Certificates; D006801:Humans; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000453:epidemiology; D012140:Respiratory Tract Diseases / Q000453:epidemiology*; D012907:Smoking; D014481:United States