Skip to main content

Table 4 Basic data about the investigated pulp mill workers employed at any time between 1970 and 2000, by smoking status

From: Incidence of chronic bronchitis in a cohort of pulp mill workers with repeated gassings to sulphur dioxide and other irritant gases

 

All¤

Never-smokers

Ever-smokers

Former smokers

Current smokers

(N = 3,060)

(N = 1,560)

(N = 1,459)

(N = 1,064)

(N = 395)

Mean age at follow-up, yrs (SD)

46.9 (12.4)

43.5 (12.5)

50.6 (11.2)***

51.5 (11.1)***

48.1 (11.0)***

Atopy, % (N)

18.4% (564)

21.2% (331)

15.4% (224)***

15.1% (161)***

16.0% (63)*

Physician-diagnosed asthma, % (N)

7.1% (216)

7.6% (118)

6.5% (95)

6.4% (68)

6.8% (27)

Adult chronic bronchitis, % (N)

5.4% (164)

4.0% (63)

6.9% (101)**

5.6% (60)

10.4% (41)***

Pack-years among current and former smokers, mean (SD)

NA

NA

14.7 (12.4)

12.6 (11.7)

20.4 (12.3)***

Any exposure to irritant gases, % (N)

48.2% (1,476)

47.4% (740)

49.6% (724)

51.2% (545)

45.3% (179)

Gassings, % (N)

39.8% (1217)

37.8% (590)

42.3% (617)*

44.4% (472)**

36.7% (145)

Frequent gassings, % (N)

11.5% (351)

10.2% (159)

12.9% (188)*

13.6% (145)**

10.9% (43)

Unexposed workers, % (N)

51.8% (1,584)

52.6% (820)

50.4% (735)

48.8% (519)

54.7% (216)

Person-years at risk, sum

57,977

26,548

30,722

22,677

8,045

Person-years at risk, mean (SD)

19.1 (9.1)

17.1 (9.3)

21.3 (8.3)***

21.6 (8.2)***

20.7 (8.8)***

  1. ¤41 subjects with unknown smoking status could not be classified in smoking categories.
  2. Compared to never-smokers *p < 0.05, **p < 0.01, ***p < 0.0001.
  3. NA Not applicable, SD Standard deviation.