{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T04:25:34Z","timestamp":1772252734374,"version":"3.50.1"},"reference-count":26,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2022,3,14]],"date-time":"2022-03-14T00:00:00Z","timestamp":1647216000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>Objective: Our goal is to evaluate the effects of heat and ultraviolet (UV) irradiation on P3 facial respirator microstructure. Intervention: P3 facial filters were exposed to dry heat and UV sterilization procedures. Methods: P3 facial filter samples underwent a standardized sterilization process based on dry heat and UV irradiation techniques. We analyzed critical parameters of internal microstructure, such as fiber thickness and porosity, before and after sterilization, using 3D data obtained with synchrotron radiation-based X-ray computed microtomography (micro-CT). The analyzed filter has two inner layers called the \u201cfiner\u201d and \u201ccoarser\u201d layers. The \u201cfiner\u201d layer consists of a dense fiber network, while the \u201ccoarser\u201d layer has a less compact fiber network. Results: Analysis of 3D images showed no statistically significant differences between the P3 filter of the controls and the dry heat\/UV sterilized samples. In particular, averages fiber thickness in the finer layer of the control and the 60\u00b0 dry heated and UV-irradiated sample groups was almost identical. Average fiber thickness for the coarser layer of the control and the 60\u00b0 dry heated and UV-irradiated sample groups was very similar, measuring 19.33 \u00b5m (\u00b10.47), 18.33 \u00b5m (\u00b10.47), and 18.66 \u00b5m (\u00b10.47), respectively. There was no substantial difference in maximum fiber thickness in the finer layers and coarser layers. For the control group samples, maximum thickness was on average 11.43 \u00b5m (\u00b11.24) in the finer layer and 59.33 \u00b5m (\u00b16.79) in the coarser layer. Similarly, the 60\u00b0 dry heated group samples were thickened 12.2 \u00b5m (\u00b10.21) in the finer layer and 57.33 \u00b5m (\u00b11.24) in the coarser layer, while for the UV-irradiated group, the mean max thickness was 12.23 \u00b5m (\u00b10.90) in the finer layer and 58.00 \u00b5m (\u00b16.68) in the coarser layer. Theoretical porosity analysis resulted in 74% and 88% for the finer and coarser layers. The finer layers\u2019 theoretical porosity tended to decrease in dry heat and UV-irradiated samples compared with the respective control samples. Conclusions: Dry heat and UV sterilization processes do not substantially alter the morphometry of the P3 filter samples\u2019 internal microstructure, as studied with micro-CT. The current study suggests that safe P3 filter facepiece reusability is theoretically feasible and should be further investigated.<\/jats:p>","DOI":"10.3390\/ijerph19063435","type":"journal-article","created":{"date-parts":[[2022,3,15]],"date-time":"2022-03-15T03:06:10Z","timestamp":1647313570000},"page":"3435","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Reusability of P3 Facial Filter in a Pandemic Emergency: A 3D Analysis of Filter Microstructure with X-ray Microtomography Images after Dry Heat and UV Sterilization Procedures"],"prefix":"10.3390","volume":"19","author":[{"given":"Luca","family":"Borro","sequence":"first","affiliation":[{"name":"Advanced Cardiothoracic Imaging Unit, Department of Imaging, Bambino Ges\u00f9 Children\u2019s Hospital, IRCCS, 00165 Rome, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Massimiliano","family":"Raponi","sequence":"additional","affiliation":[{"name":"Medical Direction, Bambino Ges\u00f9 Children\u2019s Hospital, IRCCS, 00165 Rome, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3848-412X","authenticated-orcid":false,"given":"Andrea","family":"Del Fattore","sequence":"additional","affiliation":[{"name":"Bone Physiopathology Research Unit, Genetics and Rare Diseases Research Area, Bambino Ges\u00f9 Children\u2019s Hospital, IRCCS, 00165 Rome, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2160-6194","authenticated-orcid":false,"given":"Franco","family":"Zanini","sequence":"additional","affiliation":[{"name":"Elettra-Sincrotrone Trieste, 34149 Trieste, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Francesca","family":"di Lillo","sequence":"additional","affiliation":[{"name":"Elettra-Sincrotrone Trieste, 34149 Trieste, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6563-2330","authenticated-orcid":false,"given":"Adriano","family":"Contillo","sequence":"additional","affiliation":[{"name":"Elettra-Sincrotrone Trieste, 34149 Trieste, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9011-0793","authenticated-orcid":false,"given":"Veronica","family":"Bordonaro","sequence":"additional","affiliation":[{"name":"Advanced Cardiothoracic Imaging Unit, Department of Imaging, Bambino Ges\u00f9 Children\u2019s Hospital, IRCCS, 00165 Rome, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eleonora","family":"Di Piazza","sequence":"additional","affiliation":[{"name":"UOC Endocrinologia e Diabetologia, Dipartimento di Scienze Mediche e Chirurgiche, Fondazione Policlinico Universitario A. Gemelli\u2013IRCCS, 00168 Rome, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6884-984X","authenticated-orcid":false,"given":"Alberto E.","family":"Tozzi","sequence":"additional","affiliation":[{"name":"Multifactorial and Complex Diseases Research Area, Bambino Ges\u00f9 Children\u2019s Hospital, 00165 Rome, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2611-8061","authenticated-orcid":false,"given":"Aurelio","family":"Secinaro","sequence":"additional","affiliation":[{"name":"Advanced Cardiothoracic Imaging Unit, Department of Imaging, Bambino Ges\u00f9 Children\u2019s Hospital, IRCCS, 00165 Rome, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,3,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1275","DOI":"10.1007\/s00259-020-04735-9","article-title":"Imaging and clinical features of patients with 2019 novel coronavirus SARS-CoV-2","volume":"47","author":"Xu","year":"2020","journal-title":"Eur. J. Nucl. Med. Mol. Imaging"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Aliabadi, A.A., Rogak, S.N., Green, S.I., and Bartlett, K.H. (2010, January 12\u201318). CFD simulation of human coughs and sneezes: A study in droplet dispersion, heat, and mass transfer. Proceedings of the ASME International Mechanical Engineering Congress and Exposition, Vancouver, BC, Canada.","DOI":"10.1115\/IMECE2010-37331"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"411","DOI":"10.15585\/mmwr.mm6914e1","article-title":"Presymptomatic Transmission of SARS-CoV-2-Singapore","volume":"69","author":"Wei","year":"2020","journal-title":"Morb. Mortal. Wkly. Rep."},{"key":"ref_4","first-page":"2004973","article-title":"Stability of SARS-CoV-2 in different environmental conditions","volume":"5247","author":"Chin","year":"2020","journal-title":"Lancet Microbe"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"h694","DOI":"10.1136\/bmj.h694","article-title":"Facemasks for the prevention of infection in healthcare and community settings","volume":"350","author":"MacIntyre","year":"2015","journal-title":"BMJ"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"233","DOI":"10.3201\/eid1502.081166","article-title":"Face mask use and control of respiratory virus transmission in households","volume":"15","author":"Maclntyre","year":"2009","journal-title":"Emerg. Infect. Dis."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"676","DOI":"10.1038\/s41591-020-0843-2","article-title":"Respiratory virus shedding in exhaled breath and efficacy of face masks","volume":"26","author":"Leung","year":"2020","journal-title":"Nat. Med."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"117","DOI":"10.1093\/annhyg\/men086","article-title":"Comparison of nanoparticle filtration performance of NIOSH-approved and CE-marked particulate filtering facepiece respirators","volume":"53","author":"Rengasamy","year":"2009","journal-title":"Ann. Occup. Hyg."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Bulejko, P. (2018). Numerical comparison of prediction models for aerosol filtration efficiency applied on a hollow-fiber membrane pore structure. Nanomaterials, 8.","DOI":"10.3390\/nano8060447"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1017","DOI":"10.3390\/ma7021017","article-title":"Nanocomposite electrospun nano-fiber membranes for environmental remediation","volume":"7","author":"Homaeigohar","year":"2014","journal-title":"Materials"},{"key":"ref_11","unstructured":"(2020, May 31). Gruppo di Lavoro ISS Ambiente-Rifiuti COVID-19 2020, ii, 18 p. Rapporto ISS COVID-19 n. 3\/2020 Rev. 2. Available online: https:\/\/www.iss.it\/documents\/20126\/0\/Rapporto+ISS+COVID-19++3_2020+Rev2.pdf\/4cbaa7b5-713f-da61-2cac-03e5d3d155b3?t=1591284498239."},{"key":"ref_12","first-page":"246","article-title":"Stability of SARS Coronavirus in Human Specimens and Environment and Its Sensitivity to Heating and UV Irradiation","volume":"16","author":"Duan","year":"2003","journal-title":"Biomed. Environ. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Fischer, R.J., Morris, D.H., Sarchette, S., Matson, J., Bushmaker, T., Yinda, C.K., Seifert, S.N., Gamble, A., Williamson, B.N., and Judson, S.D. (2020). Assessment of N95 respirator decontamination and reuse for SARS-CoV-2. medRxiv.","DOI":"10.31219\/osf.io\/phcsb"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1063\/1.3478190","article-title":"The SYRMEP beamline of elettra: Clinical mammography and bio-medical applications","volume":"1266","author":"Tromba","year":"2010","journal-title":"AIP Conf. Proc."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Rigon, L. (2014). X-ray Imaging with Coherent Sources, Elsevier B.V.","DOI":"10.1016\/B978-0-444-53632-7.00209-4"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1046\/j.1365-2818.2002.01010.x","article-title":"Simultaneous phase and amplitude extraction from a single defocused image of a homogeneous object","volume":"206","author":"Paganin","year":"2002","journal-title":"J. Microsc."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"233","DOI":"10.3233\/FI-2015-1273","article-title":"Enhanced and Flexible Software Tools for X-ray Computed Tomography at the Italian Synchrotron Radiation Facility Elettra","volume":"141","author":"Brun","year":"2015","journal-title":"Fundam. Inform."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1678","DOI":"10.1017\/S1431927607074430","article-title":"Computing Local Thickness of 3D Structures with ImageJ","volume":"13","author":"Dougherty","year":"2007","journal-title":"Microsc. Microanal."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"630","DOI":"10.1109\/TSMC.1978.4310039","article-title":"Picture Thresholding Using an Iterative Selection Method","volume":"8","author":"Ridler","year":"1978","journal-title":"IEEE Trans. Syst. Man Cybern."},{"key":"ref_20","unstructured":"Rutala, W.A., Weber, D.J., and Healthcare Infection Control Practices Advisory Committee (2008). Guideline for Disinfection and Sterilization in Healthcare Facilities (2008)."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1007\/s00705-008-0264-x","article-title":"Testing thermal resistance of viruses","volume":"154","author":"Sauerbrei","year":"2009","journal-title":"Arch. Virol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"509","DOI":"10.1080\/15459624.2015.1018518","article-title":"Effects of Ultraviolet Germicidal Irradiation (UVGI) on N95 Respirator Filtration Performance and Structural Integrity","volume":"12","author":"Lindsley","year":"2015","journal-title":"J. Occup. Environ. Hyg."},{"key":"ref_23","first-page":"815","article-title":"Evaluation of five decontamination methods for filtering facepiece respirators","volume":"53","author":"Viscusi","year":"2009","journal-title":"Ann. Occup. Hyg."},{"key":"ref_24","unstructured":"Van Dalen, G., Van Ginkel, M., and Hay, G. (2019, January 4\u20135). 3D imaging and analysis of fibrous filter sheets using X-ray microtomography and image analysis. Proceedings of the Micro-CT User Meeting, Mechelen, Belgium."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Lam, T.-N., Wu, C.-H., Huang, S.-H., Ko, W.-C., Huang, Y.-L., Ma, C.-Y., Wang, C.-C., and Huang, E.-W. (2019). Multi-Scale Microstructure Investigation for a PM2.5 Air-Filter Efficiency Study of Non-Woven Polypropylene. Quantum Beam Sci., 3.","DOI":"10.3390\/qubs3040020"},{"key":"ref_26","first-page":"301","article-title":"The porosity of masks used in medicine","volume":"47","year":"2004","journal-title":"Tekstilec"}],"container-title":["International Journal of Environmental Research and Public Health"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1660-4601\/19\/6\/3435\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T22:36:26Z","timestamp":1760135786000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1660-4601\/19\/6\/3435"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,3,14]]},"references-count":26,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2022,3]]}},"alternative-id":["ijerph19063435"],"URL":"https:\/\/doi.org\/10.3390\/ijerph19063435","relation":{"has-preprint":[{"id-type":"doi","id":"10.21203\/rs.3.rs-89217\/v1","asserted-by":"object"}]},"ISSN":["1660-4601"],"issn-type":[{"value":"1660-4601","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,3,14]]}}}