title: Epidemiological research in asthma: the need for a broad perspective.
mesh_terms: D000349:Africa; D000367:Age Factors; D001208:Asia; D001249:Asthma / Q000453:epidemiology* / Q000209:etiology; D003430:Cross-Sectional Studies; D004739:England; D004812:Epidemiologic Methods; D005060:Europe; D006632:Histamine; D006801:Humans; D016210:Methacholine Chloride; D008688:Methacholine Compounds; D009656:North America; D012424:Rural Population; D014505:Urban Population
chemical_list: D008688:Methacholine Compounds; D016210:Methacholine Chloride; D006632:Histamine