en Environmental Health, Sciences, and Engineering Environmental Health, Sciences, and Engineering پژوهشي Original Article <div><span style="line-height:1;"><span style="font-size:14px;"><span style="font-family:Times New Roman;"><b>Background:</b> During the early days of COVID-19 pandemic, due to the shortage of N95 respirators in hospitals and healthcare centers, the reuse of N95 respirators was posed as a crisis capacity strategy. Several studies have evaluated the efficacy of various decontamination methods on N95 respirators of well-known and approved brands. However, fundamental question is whether decontamination and reuse methods can be applied to all types of respirators.</span></span></span></div> <div><span style="line-height:1;"><span style="font-size:14px;"><span style="font-family:Times New Roman;"><b><span style="color:black">Methods:</span></b><span style="color:black"> Six types of respirators were selected from well-known and lesser-known brands which their manufacturers claimed to be N95. The selected respirators decontaminated with dry heat,</span><span lang="EN" style="color:black"> ultraviolet germicidal irradiation,</span><span style="color:black"> and </span><span lang="EN" style="color:black">ethylene oxide methods</span><span style="color:black"> in seven consecutive cycles and their </span><span lang="EN" style="color:black">particle</span> <span lang="EN" style="color:black">filtration efficiency </span><span style="color:black">and pressure drop were measured before and after each decontamination cycle.</span><br> <b><span style="color:black">Results:</span></b><span style="color:black"> As the initial measurements revealed, 4 respirators (group A) showed a sharp drop in efficiency and also, negative efficiency in removing 2.5 and 4 &micro;m particles in most of the experiments. In these respirators (group A), the maximum efficiency in removing 0.5 &micro;m particles was 74.4 %, while the last two respirators (group B) achieved an efficiency of 98 %. Subsequent experiments following the decontamination process revealed that the non-authentic N95 respirators within group A which were not resistant to decontamination. However, the second group demonstrated a removal rate of over 95 % of particles ranging from 0.5 to 10 &micro;m after six consecutive decontamination cycles using all three methods. The results demonstrated that </span><span lang="EN" style="color:black">ultraviolet germicidal irradiation</span><span style="color:black"> and </span><span lang="EN" style="color:black">ethylene oxide</span><span style="color:black"> methods could eradicate the covid-19 virus from respirators.</span><br> <b><span style="color:black">Conclusion:</span></b><span style="color:black"> The results indicated that decontamination can be successfully applied to original N95 respirators, not low-quality respirators, even under critical conditions.</span></span></span></span></div> SARS-CoV-2, Respirator, Decontamination, Particle, N95, 33 43 http://jhehp.zums.ac.ir/browse.php?a_code=A-10-39-5&slc_lang=en&sid=1 Zohre Farahmandkia zfarahmand@zums.ac.ir 100319475328460013983 0000000290224969 No Department of Environmental Health, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran. Leila Ghorbani leilaghorbani14@yahoo.com 100319475328460013984 100319475328460013984 No Department of Environmental Health, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran. Hessam Mirshahabi mirshahabi@zums.ac.ir 100319475328460013985 100319475328460013985 No Department of Microbiology and Virology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. Mohammad Reza Mehrasbi zmehr@zums.ac.ir 100319475328460013986 0000000292514513 Yes Department of Environmental Health, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran.