Zi Yang Jiang1, Zhen Huang1, Isaac Schmale2, Eric L Brown3, Michael C Lorenz4, Scott J Patlovich5, Karan Goswami6, Hannah B Wilson4, Jumah Ahmad1, Ronda Alexander1, William Bryan5, Luke Burke1, Martin J Citardi1, Jose Elias1, Tang Ho1, Jack Jacob5, Garren Low1, Pedro Miramón4, Aniruddha U Patki1, William C Yao1, Amber U Luong7. 1. Department of Otorhinolaryngology-Head and Neck Surgery, McGovern Medical School, Houston, TX, USA. 2. Department of Otolaryngology Head and Neck Surgery, University of Rochester, Rochester, NY, USA. 3. Department of Epidemiology, Human Genetics and Environmental Sciences, The University of Texas School of Public Health, Houston, TX, USA. 4. Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center, Houston, TX, USA. 5. Office of Safety, Health Environment, and Risk Management, The University of Texas Health Science Center at Houston, Houston, TX, USA. 6. Rothman Orthopaedic Institute at Thomas Jefferson University, Philadelphia, PA, USA. 7. Department of Otorhinolaryngology-Head and Neck Surgery, McGovern Medical School, Houston, TX, USA; Center for Immunology and Autoimmune Diseases, Institute of Molecular Medicine, McGovern Medical School at The University of Texas Health Science Center, Houston, TX, USA. Electronic address: amber.u.luong@uth.tmc.edu.
Abstract
PURPOSE: To evaluate the effectiveness and ease of N95 respirator decontamination methods in a clinic setting and to identify the extent of microbial colonization on respirators associated with reuse. METHODS: In a prospective fashion, N95 respirators (n = 15) were randomized to a decontamination process (time, dry heat, or ultraviolet C light [UVC]) in outpatient clinics. Each respirator was re-used up to 5 separate clinic sessions. Swabs on each respirator for SARS-CoV-2, bacteria, and fungi were obtained before clinic, after clinic and post-treatment. Mask integrity was checked after each treatment (n = 68). Statistical analyses were performed to determine factors for positive samples. RESULTS: All three decontamination processes reduced bacteria counts similarly. On multivariate mixed model analysis, there were an additional 8.1 colonies of bacteria (95% CI 5.7 to 10.5; p < 0.01) on the inside compared to the outside surface of the respirators. Treatment resulted in a decrease of bacterial load by 8.6 colonies (95% CI -11.6 to -5.5; p < 0.01). Although no decontamination treatment affected the respirator filtration efficiency, heat treatments were associated with the breakdown of thermoplastic elastomer straps. Contamination with fungal and SARS-CoV-2 viral particles were minimal to non-existent. CONCLUSIONS: Time, heat and UVC all reduced bacterial load on reused N95 respirators. Fungal contamination was minimal. Heat could permanently damage some elastic straps making the respirators nonfunctional. Given its effectiveness against microbes, lack of damage to re-treated respirators and logistical ease, UVC represents an optimal decontamination method for individual N95 respirators when reuse is necessary.
PURPOSE: To evaluate the effectiveness and ease of N95 respirator decontamination methods in a clinic setting and to identify the extent of microbial colonization on respirators associated with reuse. METHODS: In a prospective fashion, N95 respirators (n = 15) were randomized to a decontamination process (time, dry heat, or ultraviolet C light [UVC]) in outpatient clinics. Each respirator was re-used up to 5 separate clinic sessions. Swabs on each respirator for SARS-CoV-2, bacteria, and fungi were obtained before clinic, after clinic and post-treatment. Mask integrity was checked after each treatment (n = 68). Statistical analyses were performed to determine factors for positive samples. RESULTS: All three decontamination processes reduced bacteria counts similarly. On multivariate mixed model analysis, there were an additional 8.1 colonies of bacteria (95% CI 5.7 to 10.5; p < 0.01) on the inside compared to the outside surface of the respirators. Treatment resulted in a decrease of bacterial load by 8.6 colonies (95% CI -11.6 to -5.5; p < 0.01). Although no decontamination treatment affected the respirator filtration efficiency, heat treatments were associated with the breakdown of thermoplastic elastomer straps. Contamination with fungal and SARS-CoV-2 viral particles were minimal to non-existent. CONCLUSIONS: Time, heat and UVC all reduced bacterial load on reused N95 respirators. Fungal contamination was minimal. Heat could permanently damage some elastic straps making the respirators nonfunctional. Given its effectiveness against microbes, lack of damage to re-treated respirators and logistical ease, UVC represents an optimal decontamination method for individual N95 respirators when reuse is necessary.
Authors: Neeltje van Doremalen; Trenton Bushmaker; Dylan H Morris; Myndi G Holbrook; Amandine Gamble; Brandi N Williamson; Azaibi Tamin; Jennifer L Harcourt; Natalie J Thornburg; Susan I Gerber; James O Lloyd-Smith; Emmie de Wit; Vincent J Munster Journal: N Engl J Med Date: 2020-03-17 Impact factor: 91.245
Authors: Elena Scaglione; Gianluigi De Falco; Giuseppe Mantova; Valeria Caturano; Alessia Stornaiuolo; Andrea D'Anna; Paola Salvatore Journal: Int J Environ Res Public Health Date: 2022-03-11 Impact factor: 3.390