Effective inactivation of Bacillus atrophaeus spores and Escherichia coli on disposable face masks using ultraviolet laser irradiation

Abstract

Due to the widespread emergence of COVID-19, face masks have become a common tool for reducing transmission risk between people, increasing the need for sterilization methods against mask-contaminated microorganisms. In this study, we measured the efficacy of ultraviolet (UV) laser irradiation (266 nm) as a sterilization technique against Bacillus atrophaeus spores and Escherichia coli on three different types of face mask. The UV laser source demonstrated high penetration of inner mask layers, inactivating microorganisms in a short time while maintaining the particle filtration efficiency of the masks. This study demonstrates that UV laser irradiation is an efficient sterilization method for removing pathogens from face masks.

Self-Sanitization in a Silk Nanofibrous Network for Biodegradable PM0.3 Filters with In Situ Joule Heating

“…The self-sanitizable characteristics of face masks are examined by incubating Gram-negative E. coli bacteria on the surface of the SNN. 17 The surface morphology of the cultured E. coli bacteria is depicted using FESEM, as shown in Figure 6a,b. The cultured bacteria on the SNN revealed a smooth surface morphology, signifying the existence of healthy and alive E. coli bacteria.…”

“…15,16 Standard sanitization methods can harm mask filters and filtration efficiency (FE), making it crucial to sanitize masks effectively without compromising their ability to filter PM. 17 Face masks have become a fundamental aspect of everyday life because of the negative impact of airborne pollutants and the significant role of PM 0.3 in disease transmission. 12 Ensuring effective filtration and safe reusability of face masks, achieved through proper sanitization, is critical for combating disease transmission and mitigating air pollution.…”

“…In recent decades, rapid industrialization and urbanization have negatively impacted the natural atmosphere by increasing airborne particulate matter (PM) pollutants. − Specifically, PM smaller than 10 μm (PM 10 ) adversely affects human health. − Particles as small as 1.0 μm (PM 1.0 ) can be filtered using masks, but submicron PM 0.3 particles, which can carry pathogens, are the most concerning as they can penetrate the respiratory tract and bloodstream, leading to infectious diseases. , The global COVID-19 pandemic, caused by the SARS-COV-2 virus (∼120 nm in size), highlights the importance of aerosolized PM 0.3 in transmitting the virus . The World Health Organization (WHO) recommended using face masks to curb the spread of the virus, making masks crucial for safeguarding against transmissible diseases and reducing air pollution. , Conventional face masks are typically made from fibrous polypropylene, but extended use can degrade their ability to capture pathogens and PM, which raises concerns about reusability. , Moreover, pathogens captured on mask surfaces remain active for days, posing a risk of secondary transmission. , Standard sanitization methods can harm mask filters and filtration efficiency (FE), making it crucial to sanitize masks effectively without compromising their ability to filter PM . Face masks have become a fundamental aspect of everyday life because of the negative impact of airborne pollutants and the significant role of PM 0.3 in disease transmission .…”

“…Face masks are sanitized to eliminate pathogens using various methods such as dry heat, chemical reagents, nanoparticle implantation, and exposure to steam, supercritical CO 2 , UV, and solar irradiation. − While dry heat and steam offer simple sanitization of face masks, the continuous temperature rise can lower filtration performance . Conversely, UV and solar light irradiation effectively neutralize pathogens without compromising FE. , However, high-power UV requires specific chambers, and light irradiation may partially disinfect due to limited penetration. , Chemical sanitization involves agents like detergent, alcohol (IPA and ethanol), H 2 O 2 , hypochlorite, and ethylene oxide, ensuring thorough disinfection . Nevertheless, these harsh chemicals disrupt mask filtration and leave harmful residues that distress the wearer’s skin .…”

“…22 Conversely, UV and solar light irradiation effectively neutralize pathogens without compromising FE. 17,23 However, highpower UV requires specific chambers, and light irradiation may partially disinfect due to limited penetration. 24,25 Chemical sanitization involves agents like detergent, alcohol (IPA and ethanol), H 2 O 2 , hypochlorite, and ethylene oxide, ensuring thorough disinfection.…”