Field performance measurements of half-facepiece respirators--foundry operations

A series of field studies was conducted to measure workplace protection factors (WPF) provided by elastomeric and disposable half-facepiece respirators against different particulate contaminants. The research protocol developed for the study has been described in a previous article. This article presents results from dust and fume exposures at three foundries. The major components of the airborne exposures in these foundries were zinc, lead, and silicon. The major components of the in-facepiece samples were zinc, chlorine, and lead. Significant differences were observed in ambient zinc and lead concentration levels among foundries; however, no significant difference was observed in the in-facepiece concentrations of these elements among foundries. Respirator performance varied within each foundry, but there was no difference in performance when pooling all foundry data. The 5th, 10th and 50th percentile estimates for the pooled foundry and respirator WPF data were about 9, 16, and 114 respectively. The infacepiece concentration data clearly indicate that dust-fume-mist (DFM) class half-facepiece respirators, when conscientiously used, worn, and maintained, in conjunction with other existing controls in these foundries, provided effective worker protection.