| Parameters | FEV1 (% predicted) | ΔFEV1 (% predicted) | ||||
| Conventional asphalt workers | 99.9 (13.3) | 99.1 (12.5) | 0.16 | −0.7 (5.5) | 0.6 (−0.9 to 2.0) | 0.43 |
| CRM asphalt workers | 100.7 (12.8) | 99.1 (11.8) | 0.05 | −1.6 (5.4) | −0.6 (−2.6 to 1.3) | 0.51 |
| Controls | 97.6 (12.1) | 96.2 (12.3) | 0.008 | −1.3 (4.7) | Ref | Ref |
*Absolute change of FVC (% predicted) and FEV1 (% predicted) from preworking on Monday morning to postworking on Thursday afternoon; for example, ΔFVC (% predicted)=FVC (% predicted) (Thursday afternoon) − FVC (% predicted) (Monday morning). There were no missing data on lung function parameters.
†P values were derived from paired t-test.
‡β and p values were derived from general linear regression with smoking history, cigarette pack-year, allergy and pre-exposure FVC (% predicted) (or FEV1 (% predicted)) as adjustments.
CRM, crumb rubber modified; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; ref, reference.