Effects of graduated external filters on smoking cessation.
D000328:Adult; D002248:Carbon Monoxide / Q000032:analysis; D005260:Female; D006801:Humans; D008297:Male; D008722:Methods; D009538:Nicotine; D010919:Placebos; D012120:Respiration Disorders / Q000209:etiology; D012907:Smoking; D013638:Tars; D014029:Tobacco Use Disorder / Q000628:therapy*
D010919:Placebos; D013638:Tars; D009538:Nicotine; D002248:Carbon Monoxide