Change in peak expiratory flow over time among workers exposed to polyvinyl chloride dust

OBJECTIVE: To evaluate the variation of peak expiratory flow (PEF) over a working week among nonsmoking workers without previous asthma who have been exposed to polyvinyl chloride (PVC) dust. DESIGN: We conducted a cross-sectional study among 42 operators with exposure to PVC dust (filling hoppers to feed extrusion machines) and 23 employees without exposure to PVC dust in a plant producing PVC pipes in West Africa. A pre-tested questionnaire was administered and PEF was measured using a portable peak flow meter after a day off (day 1), on day 3 and at the end of the week (day 6). RESULTS: The two groups did not differ by age or body mass index. Dyspnoea was more prevalent in exposed workers than controls (52% vs. 13%, P = 0.002). PEF decreased more significantly in exposed workers than controls (-8% vs. -3% on day 3 and -10% vs. -5% on day 6, both P=0.004). The duration of exposure did not affect PEF variability in the exposed groups. CONCLUSION: The decrease of PEF over the working week in workers exposed to PVC dust is consistent with occupational asthma, although standard measures to diagnose occupational asthma were not used. This result reinforces the need to prevent excessive exposure to PVC dust.