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. 2020 Feb 12;15:323–334. doi: 10.2147/COPD.S235106

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© 2020 Melbye et al.

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Prevalence of daily smoking by age^a in three Tromsø Study surveys.^b

Notes: ^aP<0.001 in all three surveys. ^bThe statistical significance of change between the surveys is shown in Table 1.