en Occupational Health Review Article <div style="text-align: justify;"><span style="font-size:10pt"><span style="line-height:150%"><span courier="" new="" style="font-family:"><span style="color:black"><b><span style="font-size:11.0pt"><span style="line-height:150%"><span arial="" style="font-family:">Background: </span></span></span></b><span style="font-size:11.0pt"><span style="line-height:150%"><span arial="" style="font-family:">Recent years have seen many attempts to increase the efficiency and reduce the pressure drop of High-Efficiency Particulate Air Filter (HEPA) filters in removing microorganisms through shape change and the use of photocatalysts. This study is the first scoping review of the effects of photocatalysts on increasing the efficiency of HEPA filters in the elimination of airborne microorganisms. </span></span></span></span></span></span></span><br> <span style="font-size:10pt"><span style="line-height:150%"><span courier="" new="" style="font-family:"><span style="color:black"><b><span style="font-size:11.0pt"><span style="line-height:150%"><span arial="" style="font-family:">Materials and Methods:</span></span></span></b><span style="font-size:11.0pt"><span style="line-height:150%"><span arial="" style="font-family:"> PubMed, Scopus, Irandoc, and Magiran databases were searched for relevant articles. Based on select keywords and the study objectives and applying the inclusion and exclusion criteria, eight from a total of 315 articles were identified, two of which were typical in the review of efficiency and pressure drop. These articles investigated the effect of photocatalyst and filter shape on the efficiency and pressure drop of HEPA filters. </span></span></span></span></span></span></span><br> <span style="font-size:10pt"><span style="line-height:150%"><span courier="" new="" style="font-family:"><span style="color:black"><b><span style="font-size:11.0pt"><span style="line-height:150%"><span arial="" style="font-family:">Results:</span></span></span></b><span style="font-size:11.0pt"><span style="line-height:150%"><span arial="" style="font-family:"> These studies were released from 2000 to 2021. TiO2, with its long-term interactions with microorganisms, the attack of superoxide radicals (O2&bull;&minus;), and the release of K+, RNA, proteins, and other essential components will cause their destruction. Ultraviolet rays at a wavelength of 254 nm remove bacteria on the surface of the filter. The synergy of the inherent ability of UV radiation with TiO2 through nucleic acid and protein damage in microorganisms and the generation of oxidative radicals increases the efficiency of HEPA filters compared to either one alone. </span></span></span></span></span></span></span><br> <span style="font-size:10pt"><span style="line-height:150%"><span courier="" new="" style="font-family:"><span style="color:black"><b><span style="font-size:11.0pt"><span style="line-height:150%"><span arial="" style="font-family:">Conclusion:</span></span></span></b><span style="font-size:11.0pt"><span style="line-height:150%"><span arial="" style="font-family:"> The photocatalysts with ultra-violet rays on the HEPA filter can reduce the problem of microorganism growth and increase indoor air quality.</span></span></span></span></span></span></span></div> HEPA,TIO2,UV,Microorganisms,Efficiency, 201 212 http://johe.rums.ac.ir/browse.php?a_code=A-10-53-5&slc_lang=en&sid=1 Akbar Ahmadi Asour asour50@yahoo.com 22400319475328460010733 22400319475328460010733 No Ph.D. Student in Occupational Health and Safety, Dept. of Occupational Health Engineering, School of Health, Tehran University of Medical Sciences, Tehran, Iran; Instructor, Dept. of Occupational Health Engineering, School of Health, Sabzevar University of Medical Sciences, Razavi Khorasan, Iran. Tehran University of Medical Sciences Fatemeh Fasih-Ramandi f.fa30h@gmail.com 22400319475328460010734 22400319475328460010734 No Ph.D. Student in Occupational Health and Safety, Dept. of Occupational Health Engineering, School of Health, Tehran University of Medical Sciences, Tehran, Iran. Tehran University of Medical Sciences Mehdi Mohammadian Mohammadian@yahoo.com 22400319475328460010735 22400319475328460010735 No Ph.D. Student in Occupational Health and Safety, Dept. of Occupational Health Engineering, School of Health, Tehran University of Medical Sciences, Tehran, Iran. Tehran University of Medical Sciences Sepideh Keyvani s.keyvani90@yahoo.com 22400319475328460010736 22400319475328460010736 No Ph.D. Student in Occupational Health and Safety, Dept. of Occupational Health Engineering, School of Health, Tehran University of Medical Sciences, Tehran, Iran. Tehran University of Medical Sciences Malihe Kolahdouzi mKolahdouzi89@gmail.com 22400319475328460010737 22400319475328460010737 No Ph.D. Student in Occupational Health and Safety, Dept. of Occupational Health Engineering, School of Health, Tehran University of Medical Sciences, Tehran, Iran. Tehran University of Medical Sciences Zahra Beigzadeh zahrabeigzadeh90@gmail.com 22400319475328460010738 22400319475328460010738 No Ph.D. Student in Occupational Health and Safety, Dept. of Occupational Health Engineering, School of Health, Tehran University of Medical Sciences, Tehran, Iran. Tehran University of Medical Sciences Farideh Golbabaei golbabaei@tums.ac.ir 22400319475328460010739 22400319475328460010739 Yes Professor, Dept. of Occupational Health Engineering, School of Health, Tehran University of Medical Sciences, Tehran, Iran. Tehran University of Medical Sciences