Table 5 Number of cases (N), incidence rates (IRs) per 1,000 person-years and hazard ratios (HRs)*, with 95% confidence intervals (CI), for chronic bronchitis during and after employment time, 1970–2000, according to reported exposure and gassings to chemical irritants among pulp mill workers, by smoking status

3.1/1,000 (95)

1.9 (1.3–2.8)

3.1/1,000 (42)

3.0 (1.5–6.1)

3.3/1,000 (53)

1.5 (0.9–2.4)

3.5/1,000 (89)

2.1 (1.4–3.1)

3.5/1,000 (39)

3.7 (1.8–7.7)

3.6/1,000 (50)

1.6 (0.97–2.5)

2.5/1,000 (43)

1.6 (1.03–2.5)

1.9/1,000 (15)

2.4 (1.03–5.7)

3.0/1,000 (28)

1.3 (0.8–2.3)

5.9/1,000 (46)

3.2 (2.0–5.2)

7.5/1,000 (24)

8.7 (3.5–22)

4.9/1,000 (22)

1.9 (1.1–3.5)

1.5/1,000 (42)

1.0

0.9/1,000 (12)

1.0

2.1/1,000 (30)

1.0