Performance of a novel real-time respirator seal integrity monitor on firefighters: Simulated workplace pilot study

Abstract

Millions of workers, including firefighters, use respiratory protective device. The key aspect in assuring the intended protection level of a respirator is its fit. However, even if the respirator originally fits well, the faceseal may be breached during its use. Until now, there have been no practically viable, inexpensive means to monitor the performance of a respirator during actual use. A novel Respirator Seal Integrity Monitor (ReSIM) was developed and recently evaluated on manikins by our team. The objective of this study was to evaluate the ReSIM effectiveness on respirator-wearing firefighters exposed to aerosols while performing simulated routine operational activities. Initially, 15 subjects were recruited for the study. Following a preliminary investigation that resulted in modifications in the ReSIM prototype and testing protocol, a subset of nine firefighters was chosen for a full-scale evaluation. The testing was conducted in a 24.3-m exposure chamber using NaCl as the challenge aerosol. Controlled faceseal leaks were established by opening a solenoid valve for 10, 15, or 20 sec. Leaks were also established as the tested firefighter slightly repositioned the respirator on his/her face. During the testing, the ReSIM measured particles inside a full-face elastomeric respirator with a 72.7% leak detection sensitivity (probability of correct leak identification) and an 84.2% specificity (probability of correct identification of the intervals which are absent of any leak). After adjusting for false negatives and persistent false positives, sensitivity and specificity increased to 83.6% and 92.2%, respectively. The factors causing minor limitations in leak detection sensitivity and specificity can be attributed to variability among subjects, moisture's effect on the particle sensor, and some in-mask sampling bias. In conclusion, the ReSIM can promptly detect the breach in a respirator faceseal with high sensitivity and specificity. Due to its capability to alert the wearer of possible overexposure to hazardous aerosols, the ReSIM concept has a remarkable potential to be applied in various working environments, where respirators are used.

Does a Modified Adhesive Respirator Improve the Face Seal for Health Care Workers Who Previously Failed a Fit Test?: A Pilot Study During the Coronavirus Disease 2019 Pandemic

“…Also, even if the respirator originally fit well, the face seal may be breached during use. 7 Factors including physical activity, ventilatory rate, and head and body movements influence particle entry through face seal leaks. 2 Some studies have also suggested that N95 respirators fail to protect HCWs during strenuous activities such as performing chest compressions.…”

New respirator performance monitor (RePM) for powered air-purifying respirators

“…The RePM developed in this effort is an improved version of the ReSIM, which was introduced and validated earlier (Lepp€ anen et al 2018;Wu et al 2018). Both the ReSIM and RePM deploy the optical lightscattering principle and are capable of counting particles of $0.3 lm and larger.…”

“…A new concept integrated in a novel Respirator Seal Integrity Monitor (ReSIM) allowing a real-time monitoring of the respirator performance was recently developed and validated by Grinshpun and his University of Cincinnati team (Lepp€ anen et al 2018;Liu et al 2018;Wu et al 2018). However, this monitor utilizes a qualitative approach and was tested for FFRs only, not for PAPRs.…”