RR (95% CI) of COPD by quartiles of cumulative organic dust exposure stratified by duration of employment in wood and farming (1 year, 2 years, 3–6 years, 7–14 years and 15–40 years) with 10 years lag
| Duration of employment in wood and farming | RR crude | 95% CI | RRadj* | 95% CI |
| 1 year (n=709 199 person-years (26%)) | ||||
| No (0 mg/m3-year) | 1 | 1 | ||
| Intermediate-low (>0.03–0.81 mg/m3-year) | 1.88 | (1.57 to 2.44) | 1.00 | (0.83 to 1.20) |
| Intermediate-high (>0.81–1.61 mg/m3-year) | 1.52 | (1.26 to 1.83) | 0.81 | (0.67 to 0.98) |
| High (>1.61–9.06 mg/m3-year) | 1.66 | (1.38 to 1.99) | 0.90 | (0.75 to 1.09) |
| Per mg/m3-year† | 1.06 | (1.02 to 1.11) | 0.97 | (0.92 to 1.01) |
| 2 years (n=505 356 person-years (19%)) | ||||
| No (0 mg/m3-year) | 1 | 1 | ||
| Intermediate-low (>0.03–1.75 mg/m3-year) | 2.19 | (1.72 to 2.80) | 1.19 | (0.92 to 1.52) |
| Intermediate-high (>1.75–3.69 mg/m3-year) | 2.13 | (1.67 to 2.72) | 1.18 | (0.92 to 1.51) |
| High (>3.69–17.96 mg/m3-year) | 1.84 | (1.43 to 2.36) | 0.94 | (0.73 to 1.21) |
| Per mg/m3-year† | 1.04 | (1.01 to 1.07) | 0.98 | (0.95 to 1.01) |
| 3–6 years (n=793 201 person-years (29%)) | ||||
| Low (0–0.45 mg/m3-year) | 1 | 1 | ||
| Intermediate-low (>0.45–3.49 mg/m3-year) | 2.46 | (1.97 to 3.07) | 1.54 | (1.22 to 1.93) |
| Intermediate-high (>3.49–7.35 mg/m3-year) | 2.29 | (1.83 to 2.86) | 1.37 | (1.09 to 1.72) |
| High (>7.35–50.94 mg/m3-year) | 1.99 | (1.58 to 2.50) | 1.03 | (0.81 to 1.30) |
| Per mg/m3-year† | 1.01 | (1.00 to 1.02) | 0.98 | (0.97 to 0.99) |
| 7–14 years (n=505 925 person-years (19%)) | ||||
| Low (0–3.52 mg/m3-year) | 1 | 1 | ||
| Intermediate-low (>3.52–9.33 mg/m3-year) | 1.19 | (0.91 to 1.57) | 1.03 | (0.78 to 1.36) |
| Intermediate-high (>9.33–17.54 mg/m3-year) | 1.23 | (0.94 to 1.62) | 1.03 | (0.78 to 1.36) |
| High (>17.54–103.14 mg/m3-year) | 1.45 | (1.11 to 1.88) | 0.92 | (0.70 to 1.20) |
| Per mg/m3-year† | 1.01 | (1.00 to 1.01) | 0.99 | (0.98 to 1.00) |
| 15–40 years (n=202 950 person-years (7%)) | ||||
| Low (1.05–16.71 mg/m3-year) | 1 | 1 | ||
| Intermediate-low (>16.71–27.91 mg/m3-year) | 0.96 | (0.65 to 1.43) | 0.92 | (0.61 to 1.36) |
| Intermediate-high (>27.91–45.09 mg/m3-year) | 1.08 | (0.74 to 1.59) | 0.88 | (0.60 to 1.31) |
| High (>45.09–172.69 mg/m3-year) | 1.10 | (0.75 to 1.61) | 0.64 | (0.43 to 0.95) |
| Per mg/m3-year† | 1.00 | (0.99 to 1.01) | 0.99 | (0.98 to 1.00) |
*Adjustment for age group, calendar year and sex.
†Continuous cumulative organic dust exposure.
COPD, chronic obstructive pulmonary disease.