Objectives: To determine the risk in men and women smoking 1–4 cigarettes per day of dying from specified smoking related diseases and from any cause.
Design: Prospective study.
Setting: Oslo city and three counties in Norway.
Participants: 23 521 men and 19 201 women, aged 35–49 years, screened for cardiovascular disease risk factors in the mid 1970s and followed throughout 2002.
Outcomes: Absolute mortality and relative risks adjusted for confounding variables, of dying from ischaemic heart disease, all cancer, lung cancer, and from all causes.
Results: Adjusted relative risk (95% confidence interval) in smokers of 1–4 cigarettes per day, with never smokers as reference, of dying from ischaemic heart disease was 2.74 (2.07 to 3.61) in men and 2.94 (1.75 to 4.95) in women. The corresponding figures for all cancer were 1.08 (0.78 to 1.49) and 1.14 (0.84 to 1.55), for lung cancer 2.79 (0.94 to 8.28) and 5.03 (1.81 to 13.98), and for any cause 1.57 (1.33 to 1.85) and 1.47 (1.19 to 1.82).
Conclusions: In both sexes, smoking 1–4 cigarettes per day was associated with a significantly higher risk of dying from ischaemic heart disease and from all causes, and from lung cancer in women. Smoking control policymakers and health educators should emphasise more strongly that light smokers also endanger their health.