Decontamination and re-use of surgical masks and respirators during the COVID-19 pandemic

Abstract

Objectives: The coronavirus disease 2019 pandemic increased global demand for personal protective equipment (PPE) and resulted in shortages. The study evaluated the re-use of surgical masks and respirators by analysing their performance and safety before and after reprocessing using the following methods: oven, thermal drying, autoclave, and hydrogen peroxide plasma vapour.

Methods: In total, 45 surgical masks and 69 respirators were decontaminated. Visual integrity, air permeability, burst resistance, pressure differential and particulate filtration efficiency of new and decontaminated surgical masks and respirators were evaluated. In addition, 14 used respirators were analysed after work shifts before and after decontamination using reverse transcription polymerase chain reaction (RT-PCR) and viral culturing. Finally, reprocessed respirators were evaluated by users in terms of functionality and comfort.

Results: Oven decontamination (75 °C for 45 min) was found to be the simplest decontamination method. Physical and filtration assays indicated that all reprocessing methods were safe after one cycle. Oven decontamination maintained the characteristics of surgical masks and respirators for at least five reprocessing cycles. Viral RNA was detected by RT-PCR in two of the 14 used respirators. Four respirators submitted to viral culture were PCR-negative and culture-negative. Reprocessed respirators used in work shifts were evaluated positively by users, even after three decontamination cycles.

Conclusion: Oven decontamination is a safe method for reprocessing surgical masks and respirators for at least five cycles, and is feasible in the hospital setting.

Keywords: COVID-19; Mask reuse; Respirators; SARS-CoV-2 pandemic; Surgical masks.

Figure 1

Study flowchart.

Figure 2

Effect of 4 h of use on the performance of surgical masks (left) and respirators (right). Performance was measured by air permeability (Ap) (l/m²/s) (A, B); burst resistance (Br) (bar) (C, D); and pressure differential (Pd) (Δp) (E, F). *P < 0.05; **P < 0.01; ***P < 0.001. ns, not significant.

Figure 3

Effect of 20 min of use followed by one decontamination cycle using different methods – thermal drying (orange), hydrogen peroxide (H₂O₂) (pink), oven (green) or autoclave (purple) – on the performance of surgical masks (left) and respirators (right). New surgical masks and respirators are represented in blue. Performance was measured by air permeability (Ap) (l/m²/s) (A, B); burst resistance (Br) (bar) (C, D); and pressure differential (Pd) (Δp) (E, F). The graphics do not have the same scale. *P < 0.05; **P < 0.01; ***P < 0.001. ns, not significant.

Figure 4

Correlation of the effect of 20 min of use followed by up to five decontamination cycles in an oven (75 °C for 45 min; blue) or autoclave (red) on the performance of surgical masks (A, B, C, D, E, F) and respirators (G, H, I, J, K, L). Performance was measured by air permeability (Ap) (l/m²/s) (A, D, G, J); burst resistance (Br) (bar) (B, E, H, K); and pressure differential (Pd) (Δp) (C, F, I, L). *P < 0.05; **P < 0.01; ***P < 0.001. ns, not significant.

Figure 5

Evaluation of the physical integrity of respirators of five different brands when new and after undergoing three decontamination cycles in an oven. (A) Deltaplus PFF2. (B) Deltaplus PFF3. (C) MaskFace. (D) Tayco. (E) Proteplus. Performance was measured by air permeability (Ap) (l/m2/s), burst resistance (Br) (bar) and pressure differential (Pd) (Δp). The graphics do not have the same scale.

Figure 6

Correlation between the percentage of particulate filtration efficiency (Pfe) and decontamination cycles of surgical masks (A) and respirators (B, C) after oven decontamination (A, B; blue) and decontamination with hydrogen peroxide plasma vapour (H₂O₂; C) (red). *P < 0.05. ns, not significant.