Table 1 Characteristics of control and tobacco-exposure groups

Men (%)

59.3

9.2

95.5

63.6

62.0

61.0

Age (years)

57.9 ± 15.7

53.4 ± 14.5

56.9 ± 14.9

63.5 ± 11.2

56.6 ± 14.7

57.0 ± 15.1

Urban residence (%)

75.8

70.7

72.3

86.3

73.5

74.3

Han nationality (%)

95.4

96.6

95.6

97.8

96.2

95.9

5.5

1.6

3.2

2.1

2.5

3.6

26.0

20.1

28.4

16.6

24.1

24.8

35.1

32.9

42.1

41.8

38.9

37.5

31.7

43.9

25.1

38.4

33.2

32.6

1.8

1.6

1.3

1.2

1.4

1.5

Years exposed to passive smoking

–

30 (18–40)

–

36 (26–44)

–

–

Cigarettes passively smoked daily

–

10 (6–20)

–

10 (4–17)

–

–

Pack-years exposed to passive smoking

–

15 (6–27)

–

14 (4–27)

–

–

Years exposed to active smoking

–

–

34 (21–46)

40 (30–49)

–

–

Cigarettes actively smoked daily

–

–

10 (6–20)

10 (5–20)

–

–

Pack-years exposed to active smoking

–

–

17 (7–32)

19 (6–35)

–

–