Fig. 1From: Characterizing nicotine exposure among a community sample of non-daily smokers in the United StatesDisplay of the intraindividual variability of daily salivary cotinine values for each participant in the sample. For display purposes, the sample was grouped into tertiles based on each participant’s mean cotinine value. Each line represents the daily salivary cotinine (ng/ml) values for a single participantBack to article page