Workplace Performance of a Hood-Style Supplied-Air Respirator

Abstract

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.

Criteria for the Collection of Useful Respirator Performance Data in the Workplace

“…While substitution of an analytical LOQ or a fraction thereof has been common practice, random effects, nonparametric, and censoring regression models have also been used. (29,57,58) When most or all C i samples in a study are below the quantification limit, as is often the case in studies of high-performing respirators, (17,20,23,24) meaningful WPF distributions cannot be calculated. In these cases, reporting WPFs as values “greater than” a minimum value calculated using the quantification limit as the C i mass (for example) may be most appropriate: This process avoids bias and error introduced by assumptions regarding the C i distribution or the expected level of performance (APF) for the device.…”

Primary prevention: exposure reduction, skin exposure and respiratory protection

“…Indirect evidence for effectiveness of PPE in preventing occupational asthma An updated review of the medical literature revealed indirect evidence that use of respiratory protective devices might prevent asthma onset, by demonstrating that respirators can reduce exposures to agents that can cause occupational asthma. These studies investigated: air purifying respirators [83] and half-face respirators with particulate/organic vapour/formaldehyde filters [84] used by firefighters; air purifying respirators [85], half-mask respirators with frequent cartridge changes [86], and half-face air purifying or full-face air-supplied respirators [87] for workers exposed to styrene; hood style supplied air respirators used to reduce exposure to chromium and other materials during sanding in aircraft manufacturing [88]; P2 facemasks and fresh-air helmets to reduce levels of rodent allergens among laboratory animal handlers [89]; and certified two-tie protective masks that reduced total particle concentrations by 97% in swine confinement buildings [90].…”