Avaliação da descontaminação de máscaras de proteção facial utilizando radiação UV-C

Abstract

Infectious respiratory diseases (IRD) are predominantly transmitted by airborne droplets or aerosols between people with close interactions. IRDs have a high rate of mortality and transmission between populations. The use of face protection masks (FPM) are effective in reducing the transmission of IRDs. Different methods are used for surface decontamination. The physical method of decontamination with UV-C radiation has shown effective results in different areas. The aim of this in vitro study was to evaluate FPM decontamination using UV-C radiation. Quadrangular samples from the masks were contaminated with a suspension of 108 CFU/ml of E. coli, in exponential phase, with the aid of a spray bottle inside the laminar flow. Three types of masks were evaluated (n=9): Tricoline (cotton) (T), Surgical (S) and N95 (N) at different times of UV-C irradiation, with portable SURFACE UV® equipment (MMOptics, São Carlos, Brazil, ƛ= 254 nm), the distance of 1 cm from the surface of the samples, scanning mode, at times of 30s, 45s and 60 s. To evaluate the microbial reduction, the samples were immersed in a test tube containing sterile saline solution, submitted to mechanical agitation for microbial recovery, and subsequently performed serial dilutions in the order of 1:10. Aliquots of the suspensions were seeded on Mueller Hinton agar for final microbial counts. The experiment was carried out in triplicate. All data were analyzed for their distribution by the Shapiro-Wilk test. Parametric data were analyzed by ANOVA and Tukey test. Nonparametric data were analyzed using the Kruskal-Wallis and Wilcoxon test (p< 0.05). The study showed that UV-C radiation promoted effective decontamination of different models of FPM contaminated with E. coli. In Tricoline and Surgical the microbial reduction was observed in the time of 30 s and total decontamination in the times of 45 s and 60 s. In N95, total decontamination was observed at all irradiation times. The type of face protection mask influenced the effects of UV-C. The UV-C irradiation from 30 s onwards reduced the microbial load and from 45 s onwards promoted total decontamination in all types of masks tested.