Objective To compare the protective effect of 2 types of respiratory protective equipment (RPE) against various metal particles by calculating the workplace protection factor (WPF) of RPEs worn by welders in a shipyard.
Methods A total of 18 welding workers (17 male and 1 female) from a shipyard in Shanghai participated in this study. They used the same type of PRE as they actually wore in the daily work, with 5 of them wearing filtered half masks (RPE1) and 13 wearing tri-folded anti-particulate masks (RPE2). The concentrations of metal particles inside and outside the RPE were measured using modified American WPF test method and the WPF values were computed. Pearson correlation analysis was adopted to analyze log-transformed data and a two-way nonparametric Scheirer-Ray-Hare test was used to compare the effect of 2 types of RPE against metal particles.
Results Against manganese particles and iron particles, the WPF values followed lognormal distribution, and the 5th percentile of WPF (WPF5%) were 15.01 and 13.60 with the geometric mean (GM) of 114.76 and 82.37, respectively. The WPF5% of RPE1 and RPE2 were 11.25 and 22.28, with the GM of 86.49 and 123.01, respectively. The differences of WPF values between 2 types of RPEs were not statistically significant (P > 0.05), while the differences of WPF values against two metal particles, Fe and Mn, were also not statistically significant (P > 0.05), and there was no interaction between the RPE types and metal particles on the protection effect (P > 0.05).
Conclusions The modified WPF test method can effectively test the WPF values of RPE, and the two types of RPEs tested in this study can provide protection against different metal particles with a similar effect.
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