Smoking ban in England has a dramtic impact on prevalence.
Hairon
Nerys
N
D004739:England / Q000453:epidemiology; D006801:Humans; D015995:Prevalence; D012606:Scotland / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology* / Q000331:legislation & jurisprudence*; D016540:Smoking Cessation / Q000331:legislation & jurisprudence* / Q000706:statistics & numerical data*; D014852:Wales / Q000453:epidemiology