Table 1

Smoking dose categories and corresponding relative risks (RRs) for lung cancer

Smoking doseRR
Non-smokers or never smoked daily1
≤10 pack-years in the past3
>10 pack-years in the past10
Non-daily smoker1.5
Current daily smokerAge <40Age 40–59Age ≥60
Started before age 20
 <10 cigarettes/day2.34.26.1
 10–19 cigarettes/day4.58.211.9
 ≥20 cigarettes/day7.914.320.8
Started after age 20
 <10 cigarettes/day1.73.04.4
 10–19 cigarettes/day3.25.88.5
 ≥20 cigarettes/day5.710.214.8