Table 1

Operational definitions of four phases of the tobacco epidemic (and number of countries), by sex

Incipient stage*Current prevalence <5% (80)†Current prevalence <15% (17)
Phase twoCurrent prevalence now 5%–45% and never declined, or only declined by <5% points (64)Current prevalence 15%–65% and never declined or declined by <10% points (85)
Phase threePrevalence has declined by >5% points but is still >20% (27)Prevalence has declined by >10% points, but is still >25% (52)
Phase fourPrevalence has declined by >5% points and is now <20% (33)Prevalence has declined by >10% points, and is now <25% (50)
  • *Countries at this stage, by definition, have never experienced prevalence levels that would classify them to any subsequent epidemic stage; some countries in stage 4 might have similarly low prevalence levels following extensive declines.

  • †Numbers in parentheses are the number of countries classified into each phase.