Pack size, reported cigarette smoking rates, and public health.

The relation between packs containing 25 or 20 cigarettes each and self-reports of daily cigarette intake was examined in surveys of smoking habits from the United States and Canada. More Canadian than US smokers report smoking 25 cigarettes per day (19.3 per cent vs 2.1 per cent). As market share of packs of 25 increases across six regions in North America, reports of smoking 25 cigarettes per day increase. Even if smoke exposure remains constant, smoking statistics are likely to be influenced by pack size.