Forty apparently healthy smokers and non smokers (20 male, 20 female) will be recruited by advertising in the Twin Cities area. This will be done by the Tobacco Use Research Center. They will be screened in a phone call, then invited to come in for an orientation session at which consent will be obtained. Pregnant smokers will be excluded. They will visit the clinic weekly for 2 months and once monthly for 4 months for a total of 6 months participation.