Real-time evaluation of workplace protection factors from powered air-purifying respirators

Loose-fitting powered air-purifying respirators (PAPRs) are widely used by healthcare workers to protect against inhalation hazards, as they require no fit testing. However, incorrect use can compromise their efficacy, which may progressively deteriorate over time. Therefore, there is a critical need for real-time monitoring of PAPR performance during occupational activities. In this study, a portable device called the Exposure Protection Integrated Communicator (EPIC) was developed, which uses optical particle sensors to evaluate the workplace protection provided by PAPRs. EPIC monitors concentrations inside and outside a respirator using two sensors to quantitatively calculate the protection factor (PF), defined as the ratio of particle concentrations outside to inside the respirator. The system applied algorithms to correct sensor readings and alert wearers if respirator protection was compromised. The prototype EPIC was evaluated using a manikin headform connected to a breathing recording and simulation system (BRSS) to simulate a sinusoidal breathing pattern. A PortaCount fit tester based on a single-condensation-nuclei-counter principle served as the reference measurement device during parallel tests. The results were expressed as PFs for comparison between the EPIC system and the reference method. The prototype EPIC demonstrated to be an effective tool for quantifying the real-time performance of PAPRs, particularly in environments with particle concentrations of 40,000 to 70,000 particles/L. Data collected from both the EPIC and PortaCount were compared, revealing that the EPIC could measure PFs ranging from 10 to 10,000. The EPIC showed a strong correlation with the reference PortaCount (R² = 0.84), despite the two systems using different measurement principles and detection limits. The study results confirmed the effectiveness of EPIC in quantitatively assessing respirator particle ingress.