The utility of airfed RPE in the management of workers with metal-working fluid occupational asthma

Abstract

Introduction: Respiratory Protective Equipment (RPE) is the last in the hierarchy of control, used when other methods have failed. We have investigated the benefits of air-fed RPE in workers with occupational asthma exposed to metal-working fluid aerosols in a car engine and transmission manufacturing facility. All workers had remained symptomatic after steam cleaning and replacement of the metal-working fluid. Methods: PEF records with any positive score from the Oasys program pre RPE that contained a minimum of 5 day shifts and 3 restdays pre and post RPE were included. The Area Between Curves (ABC) score (which compares the area between the mean 2-hourly PEF result on rest and work days) from Oasys was used to assess the efficacy of the RPE. Results: 20 workers met inclusion criteria. Records were kept for a mean of 24.6 day-shifts and restdays before and 24.7 after the institution of RPE. The ABC score improved from 26.6 (SD 16.2) to 17.7 (SD 25.4) litres/min/hour (p=0.052) post RPE; however the work-related decline was Conclusion: Serial PEF measurements assessed with the ABC score from the Oasys system allowed quantification of the effect of RPE in sensitised workers. The RPE reduced falls in PEF associated with work exposure, which was rarely complete, but was within “normal” limits in 65% of workers, the remaining 7 workers had significant falls in PEF despite rigorously applied RPE. This study suggests that RPE use cannot be relied on to replace source control in workers with occupational asthma, and that monitoring post RPE introduction is needed.