Efficacy of Ambulance Air Purifiers with Different Photocatalytic Oxidation Components in the Removal of Bacillus subtilis Spores.

Efficacy of Ambulance Air Purifiers with Different Photocatalytic Oxidation Components in the Removal of Bacillus subtilis Spores. | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Efficacy of Ambulance Air Purifiers with Different Photocatalytic Oxidation Components in the Removal of Bacillus subtilis Spores. Akkrapol Poohpajit, Santisith Khiewkhern, Chuleewan Thunyasirinon, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7727840/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 17 Jan, 2026 Read the published version in Scientific Reports → Version 1 posted 10 You are reading this latest preprint version Abstract Ambulances are enclosed environments that carry a high risk of airborne and surface microbial transmission, yet effective disinfection technologies remain limited. This study evaluated four photocatalytic oxidation (PCO) configurations—O₃+UVA+TiO₂, UVA+TiO₂, O₃+UVC+ZnO, and UVC+ZnO—against B. subtilis spores. Experiments were conducted in a laboratory-simulated ambulance cabin (8.998 m³), where spores at 1.5×10⁸ CFU/mL (8 mL) were spray misted using a nebulizer and sampled using an Andersen Impactor, following the NIOSH method. Disinfection efficacy was quantified as the percentage reduction of B. subtilis spores in the air and on surfaces. Among the tested systems, efficacy ranked as UVA+TiO₂ > O₃+UVA+TiO₂ > O₃+UVC+ZnO > UVC+ZnO. UVA+TiO₂ achieved the most rapid and stable disinfection, reducing airborne spores by >80% within 15 minutes, achieving complete removal within 90 minutes, and reducing surface contamination by 96.77% at 120 minutes. In contrast, ZnO- and UVC-based systems exhibited lower or inconsistent performance. These findings identify UVA+TiO₂ photocatalysis as a safe, ozone-free, and highly effective strategy for ambulance air purification. Its rapid and durable antimicrobial action demonstrates clear advantages over approaches based on ozone or UVC, offering practical benefits for infection control in emergency medical services and providing a foundation for further optimization of photocatalytic technologies in healthcare settings. Biological sciences/Biotechnology Earth and environmental sciences/Environmental sciences Physical sciences/Materials science Biological sciences/Microbiology Photocatalytic oxidation UVA/TiO₂ Ambulance disinfection Airborne disinfection Surface disinfection B.subtilis spores Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 17 Jan, 2026 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 13 Nov, 2025 Reviews received at journal 08 Nov, 2025 Reviews received at journal 05 Nov, 2025 Reviewers agreed at journal 31 Oct, 2025 Reviewers agreed at journal 31 Oct, 2025 Reviewers invited by journal 22 Oct, 2025 Editor invited by journal 01 Oct, 2025 Editor assigned by journal 30 Sep, 2025 Submission checks completed at journal 29 Sep, 2025 First submitted to journal 27 Sep, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7727840","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":538525714,"identity":"cf2ffcbc-3e37-4d72-83de-025d4a1084e0","order_by":0,"name":"Akkrapol Poohpajit","email":"","orcid":"","institution":"Mahasarakham University","correspondingAuthor":false,"prefix":"","firstName":"Akkrapol","middleName":"","lastName":"Poohpajit","suffix":""},{"id":538525716,"identity":"9fc9b7cd-6165-49c9-b081-f8cc516d9292","order_by":1,"name":"Santisith 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This study evaluated four photocatalytic oxidation (PCO) configurations—O₃+UVA+TiO₂, UVA+TiO₂, O₃+UVC+ZnO, and UVC+ZnO—against B. subtilis spores. Experiments were conducted in a laboratory-simulated ambulance cabin (8.998 m³), where spores at 1.5×10⁸ CFU/mL (8 mL) were spray misted using a nebulizer and sampled using an Andersen Impactor, following the NIOSH method. Disinfection efficacy was quantified as the percentage reduction of B. subtilis spores in the air and on surfaces. Among the tested systems, efficacy ranked as UVA+TiO₂ \u003e O₃+UVA+TiO₂ \u003e O₃+UVC+ZnO \u003e UVC+ZnO. UVA+TiO₂ achieved the most rapid and stable disinfection, reducing airborne spores by \u003e80% within 15 minutes, achieving complete removal within 90 minutes, and reducing surface contamination by 96.77% at 120 minutes. In contrast, ZnO- and UVC-based systems exhibited lower or inconsistent performance. 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