title: Chronic respiratory disease among nonsmokers in Hagerstown, Maryland. 3. Social class and chronic respiratory disease.
mesh_terms: D000293:Adolescent; D000328:Adult; D002908:Chronic Disease; D006306:Health Surveys; D006801:Humans; D007182:Income; D008297:Male; D008396:Maryland; D009017:Morbidity; D009790:Occupations; D012129:Respiratory Function Tests; D012140:Respiratory Tract Diseases / Q000453:epidemiology* / Q000401:mortality; D012189:Retrospective Studies; D012907:Smoking; D012923:Social Class