Multiple linear regression model for ΔFEV1 (ml) during the follow up period for 644 tunnel construction workers* by non-smokers and ever smokers
| Covariables | ΔFEV1 (ml) | ||
|---|---|---|---|
| b | SE | p value | |
| *Three TBM workers and one engineer, one foreman, and one outdoor worker were excluded from the final analyses. | |||
| †Cumulative exposure is adjusted for sick leave. | |||
| Never smokers (R2adjusted = 0.09) | |||
| Constant | 67 | 84 | 0.4 |
| Observation time (y) | −20 | 7.0 | <0.01 |
| Age (y) | −1.8 | 1.7 | 0.3 |
| Cumulative exposure to nitrogen dioxide† (ppm⋅y) | −39 | 9.0 | <0.001 |
| Ever smokers (R2adjusted = 0.08) | |||
| Constant | 30 | 98 | 0.8 |
| Observation time (y) | −0.73 | 7.3 | 0.9 |
| Age (y) | −4.2 | 2.2 | 0.06 |
| Cumulative exposure to nitrogen dioxide† (ppm⋅y) | −38 | 8.2 | <0.001 |