AIRWAY-OBSTRUCTION IN BOILERMAKERS EXPOSED TO FUEL-OIL ASH - A PROSPECTIVE INVESTIGATION

We prospectively investigated the lower airway response in boilermakers overhauling an oil-powered boiler. We studied 26 male boilermakers with a mean age (SD) of 43.3 (8.6) yr. Pre-exposure spirometry and methacholine challenge tests were performed before beginning the boiler overhaul; postex-posure tests were performed after approximately 4 wk of work on the boiler. Exposure to particulates with an aerodynamic diameter of 10 mu m and smaller (PM(10)) and respirable vanadium dust were estimated using daily work diaries and a personal sampling device for respirable particles. Using these estimates, we calculated average and peak exposure between pre- and postexposure tests for each subject. The average PM(10) concentration ranged from 1.44 to 6.69 mg/m(3), with a mean (SD) of 3.22 (1.42) mg/m(3); the average vanadium concentration ranged from 2.2 to 31.3, with a mean (SD) of 12.2 (9.1) mu g/m(3). The mean postexposure fall in FEV(1) was 140 +/- 160 ml (p < 0.01); 24 of 26 subjects had a drop in FEV(1). For each subject, the adjusted change in FEV(1) (Delta FEV1.adj) was calculated by dividing the change in FEV(1) by the average of the pre- and postexposure FEV(1) values. The Delta FEV1.adj was regressed, controlling age and current smoking status, on average and peak exposure to both PM(10) and vanadium. There was a dose-response relationship between average and peak PM(10) exposure and Delta FEV1.adj: beta = -0.91% per mg/m(3), p = 0.08 and beta = -1.03% per mg/m(3), p = 0.03, respectively. However, there was no relationship between Delta FEV1.adj and respirable vanadium dust concentration. Furthermore, there was no postexposure change in nonspecific airway responsiveness. In summary, we found a significant fall in FEV(1) and a dose-response relationship between Delta FEV1.adj and average and peak PM(10) exposure. This across-job drop in FEV(1) was not associated with a shift in bronchial responsiveness as measured by methacholine.