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Per-cigarette levels of cotinine (A), trans-3′-hydroxycotinine (B), total nicotine metabolites (C), average total daily puffs (D), and average total daily puff volume (E) for light-to-moderate (<20 cigarettes/day) and heavy (≥20 cigarettes/day) smokers among 332 participants from the Pennsylvania Adult Smoking Study, 2012–2014. All comparisons were significant at P < 0.01. Bars, 95% confidence intervals.
