This study evaluated the workplace performance of an N95 filtering facepiece, air-purifying respirator in a steel foundry. Air samples were collected inside and outside respirators worn by workers who were properly trained and qualitatively fit tested. For most workers, three or four pairs of air samples were collected on each of 2 days. The 49 valid sample sets were analyzed for iron, silicon, and zirconium. Only iron was present in sufficient concentrations to perform workplace protection factor (WPF) calculations. Individual WPF measurements ranged from 5 to 753. The geometric mean of the distribution was 119 with a lower 5th percentile value of 19. Time-weighted average WPFs (WPF(TWA)) were also calculated for each day for each worker as an estimate of the protection an individual might receive with daily respirator use. The WPF(TWA) values ranged from 15 for the worker with the single WPF value of 5, to a high of 684. The distribution of WPF(TWA) had a geometric mean of 120 and a lower 5th percentile of 22. Both data treatments indicate this respirator's performance was consistent with the assigned protection factor of 10 typically used for half facepiece respirators. The respirator provided adequate protection as used in this study. All contaminant concentrations inside the respirator were well below the relevant occupational exposure limits. Data collected also illustrate the dynamic nature of faceseal leakage in the workplace.

This study evaluated the workplace performance of a hood-style supplied-air respirator during aircraft sanding operations. Air samples were collected inside and outside the respirators worn by workers during normal work activities. The samples were analyzed for chromium, strontium, and magnesium. These contaminants were not detected on any inside sample from the valid sample sets. Program protection factors (PPFs) were estimated for the valid sample sets using the limit of detection as the inside sample mass. When it was possible, PPF estimates were made using each element individually and a combination of all three elements. The PPF estimates were in the range of >11000 to >65000 regardless of the elements used in the calculation. Examination of the PPF estimates for different elements reveals the differences are largely artificial. The results indicate the tested respirator performed well above its assigned protection factor of 1000. No worker was overexposed to chromium, strontium, or magnesium during the study. This study also illustrates the difficulty in locating workplaces with sufficient contaminant concentration and duration to measure the capabilities of high-performing respirators.