An Experimental Analysis of Five Household Equipment-Based Methods for Decontamination and Reuse of Surgical Masks

Abstract

The current coronavirus pandemic has increased worldwide consumption of individual protective devices. Single-use surgical masks are one of the most used devices to prevent the transmission of the COVID-19 virus. Nevertheless, the improper management of such protective equipment threatens our environment with a new form of plastic pollution. With the intention of contributing to a responsible policy of recycling, in the present work, five decontamination methods for used surgical masks that can be easily replicated with common household equipment are described. The decontamination procedures were hot water at 40 °C and 80 °C; autoclave; microwave at 750 W; and ultraviolet germicidal irradiation. After each decontamination procedure, the bacterial load reduction of Staphylococcus aureus ATCC 6538 was recorded to verify the effectiveness of these methods and, moreover, bacterial filtration efficiency and breathability tests were performed to evaluate mask performances. The best results were obtained with the immersion in 80 °C water and the microwave-assisted sterilization. Both methods achieved a high degree of mask decontamination without altering the filtration efficiency and breathability, in accordance with the quality standard. The proposed decontamination methods represent a useful approach to reduce the environmental impact of this new waste material. Moreover, these procedures can be easily reproduced with common household equipment to increase the recycling efforts.

Keywords: breathability; filtration efficiency; household equipment; microbial cleaning; reuse; type II surgical mask.

Figure 1

Pictures of the equipment used for the decontamination methods: immersion in hot water (A); exposure to autoclave steam (B); microwave-assisted sterilization (C); exposure to UVGI (D).

Figure 2

Bacterial load on soiled masks after one cycle of each decontamination method. Bacterial load (Log CFU/mL) on soiled masks after one cycle of each decontamination method. Not treated (NT); immersion in hot water at 40 °C (40 °C); immersion in hot water at 80 °C (80 °C); to autoclave steam (AC); microwave-assisted sterilization (MW) and exposure to UVGI (UVGI). Results are reported as mean ± SD of two independent experiments) (**, p < 0.01; ***, p < 0.001; ****, p < 0.0001).

Figure 3

Evaluation of bacterial filtration efficiency (BFE, %) and breathability (BRE, Pa/cm²) post decontamination methods on a soiled single-use surgical mask after the first and fifth cycle of each decontamination method. (A) immersion in hot water at 80 °C (80 °C); (B) autoclave steam (AC); (C) microwave-assisted sterilization (MW); (D) ultraviolet germicidal irradiation (UVGI). CTRL, clean surgical mask. Results are reported as mean ± SD of two independent experiments.