Risk factor

Recalled

Recognised

N

% 95% CI

N

% 95% CI

Smoking

386

95.8 93.3 - 97.5

399

99 97.5 - 99.7

Second-hand smoking

68

16.9 13.3 - 20.9

383

95 92.4 - 96.9

Air pollution

99

24.6 20.4 - 29.1

321

79.7 75.4 - 83.5

Other lung diseases

15

3.7 2.1 - 6.1

242

60.0 55.1 - 64.5

Previous lung cancer or family history of lung cancer

126

31.3 26.8 - 36.0

349

86.6 82.9 - 89.8

Chemicals

27

6.7 4.5 - 9.6

293

72.7 68.1 - 77.0

Asbestos

24

6.0 3.9 - 8.7

280

69.5 64.7 - 73.9

Radiation

18

4.5 2.7 - 7.0

259

64.3 59.4 - 69.0