Table 2

The crude and adjusted risk ratios with 95% confidence intervals of developing lung cancer among 16 209 middle aged men living in Oslo in 1972, according to level of education, type of occupation, and smoking habits

Incidence (1000/year)cRR95% CI*aRR95% CI
*Controlled for age at screening, nitrogen oxides, and the other conditions in the table.
aRR, adjusted risk ratio; CI, confidence interval; cRR, crude risk ratio; ref, reference category.
<10 years1.871 (ref)1 (ref)
10–12 years1.030.540.44 to 0.660.670.54 to 0.82
12+ years0.670.350.25 to 0.470.520.38 to 0.71
“White collar”0.901 (ref)1 (ref)
“Blue collar”
Moderate physical work1.331.501.19 to 1.871.271.00 to 1.62
Intermediate physical work1.701.921.50 to 2.471.250.94 to 1.65
Vigorous physical work1.541.751.10 to 2.791.110.68 to 1.80
Smoking habits
Non-smoker0.081 (ref)1 (ref)
1–9 cigarettes per day0.9811.904.98 to 28.3711.074.31 to 28.40
10–19 cigarettes per day1.8523.0310.20 to 51.8822.869.43 to 55.40
20+ cigarettes per day2.7935.2315.61 to 79.5036.4715.06 to 88.29
Smoker, amount not reported0.576.850.82 to 56.907.950.93 to 67.90
Former smoker0.354.241.77 to 10.144.581.79 to 11.71