Aubin et al. BMC Public Health 2010, 10:100 http://www.biomedcentral.com/1471-2458/10/100 Page 3 of 8 6 032 letters sent to a national representative sample of subjects aged 15 years and more (September to November 2006) 3 932 questionnaires returned (66%) 3 889 completed and analysed Current smokers n = 809 (21 %) Survey Wave 2 June 2007 Survey Wave 3 November 2007 Survey Wave 4 June 2008 Survey Wave 5 November 2008 Figure 1 Study Design. NON smokers Ex-smokers (n = 999) or never smoked (n = 2081)