{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,21]],"date-time":"2026-07-21T06:40:12Z","timestamp":1784616012175,"version":"3.55.0"},"reference-count":18,"publisher":"Public Library of Science (PLoS)","issue":"5","license":[{"start":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T00:00:00Z","timestamp":1778544000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:p>During the COVID-19 pandemic, airborne transmission of SARS-CoV-2 via respiratory aerosols was a critical concern in indoor environments. In the city of Santander, Spain, an outbreak in a multi-family residential building during a period of low community transmission revealed vertical clustering of 15 cases in four homes. The building\u2019s design included single interior bathrooms without windows in each home, ventilated by a shared vertical bathroom duct system. Field measurements, computational fluid dynamics (CFD) simulations, and multi-zone airflow modeling were performed to evaluate vertical disease transmission potential in the Santander building. Epidemiological and genetic data combined with the field-collected data and modeling indicated that the most plausible transmission route was the bathroom vertical ventilation duct system, which facilitated movement of infectious aerosol between vertically connected homes. Additionally, operating the kitchen exhaust fan can augment the movement of aerosols between occupied spaces increasing the potential for infection. Recommendations for mitigating future risks include the installation of forced air exhaust fans with non-return flaps in bathroom ducts.<\/jats:p>","DOI":"10.1371\/journal.pone.0345041","type":"journal-article","created":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T17:41:41Z","timestamp":1778607701000},"page":"e0345041","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":1,"title":["Potential airborne transmission of SARS-COV-2 through bathroom ventilation ducts associated with an outbreak in a residential building in Santander, Spain, 2020"],"prefix":"10.1371","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1967-7551","authenticated-orcid":true,"given":"Shelly L.","family":"Miller","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shujie","family":"Yan","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alberto","family":"Garc\u00eda","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0653-3612","authenticated-orcid":true,"given":"Liangzhu Leon","family":"Wang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhiqiang","family":"Zhai","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jose Ramon","family":"Aranda","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0879-5798","authenticated-orcid":true,"given":"Fernando","family":"Gonz\u00e1lez-Candelas","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1566-8455","authenticated-orcid":true,"given":"Ignacio","family":"Lombillo","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3980-7664","authenticated-orcid":true,"given":"Javier","family":"Balb\u00e1s","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ernesto","family":"Cabrillo","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Delf\u00edn","family":"Sili\u00f3","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"L. David","family":"Higuera","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,5,12]]},"reference":[{"key":"pone.0345041.ref001","doi-asserted-by":"crossref","first-page":"476","DOI":"10.1016\/j.ijid.2020.09.025","article-title":"Viable SARS-CoV-2 in the air of a hospital room with COVID-19 patients","volume":"100","author":"JA Lednicky","year":"2020","journal-title":"Int J Infect Dis"},{"key":"pone.0345041.ref002","doi-asserted-by":"crossref","first-page":"105730","DOI":"10.1016\/j.envint.2020.105730","article-title":"Airborne transmission of SARS-CoV-2: The world should face the reality","volume":"139","author":"L Morawska","year":"2020","journal-title":"Environ Int"},{"issue":"2","key":"pone.0345041.ref003","doi-asserted-by":"crossref","first-page":"96","DOI":"10.1111\/j.1600-0668.2004.00318.x","article-title":"Multi-zone modeling of probable SARS virus transmission by airflow between flats in Block E, Amoy Gardens","volume":"15","author":"Y Li","year":"2005","journal-title":"Indoor Air"},{"key":"pone.0345041.ref004","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/j.ijid.2020.12.035","article-title":"Possible aerosol transmission of COVID-19 associated with an outbreak in an apartment in Seoul, South Korea, 2020","volume":"104","author":"SE Hwang","year":"2021","journal-title":"Int J Infect Dis"},{"key":"pone.0345041.ref005","doi-asserted-by":"crossref","first-page":"109323","DOI":"10.1016\/j.buildenv.2022.109323","article-title":"Explosive outbreak of SARS-CoV-2 Omicron variant is associated with vertical transmission in high-rise residential buildings in Hong Kong","volume":"221","author":"VC-C Cheng","year":"2022","journal-title":"Build Environ"},{"key":"pone.0345041.ref006","unstructured":"ICANE, Instituto C\u00e1ntabro de Estad\u00edstica [2020]. Situaci\u00f3n Covid por Municipios. (updated Oct 2025). https:\/\/www.icane.es\/"},{"key":"pone.0345041.ref007","unstructured":"RTVE, Radio Televisi\u00f3n Espa\u00f1ola [2020]. 30\/06\/2020.\u00bfQu\u00e9 es el \u2018confinamiento quir\u00fargico\u2019?. (updated Oct 2025). https:\/\/www.rtve.es\/play\/videos\/la-manana\/confinamiento-quirurgico\/5613507\/"},{"key":"pone.0345041.ref008","unstructured":"Official State Gazette [1975]. Order of July 2, 1975, approving the Technological Building Standard NTE-ISV\/1975, \u201cSanitary Installations: Ventilation\u201d. (updated Oct 2025). https:\/\/www.boe.es\/buscar\/doc.php?id=BOE-A-1975-14350"},{"key":"pone.0345041.ref009","unstructured":"La Vanguardia Newspaper [2020]. \u201cCantabria detects an outbreak of three new cases in a home in Santander\u201d. (updated Oct 2025). https:\/\/www.lavanguardia.com\/local\/cantabria\/20200625\/481951373641\/cantabria-detecta-un-foco-de-tres-nuevos-casos-en-un-domicilio-de-santander.html"},{"key":"pone.0345041.ref010","unstructured":"Diario Monta\u00f1\u00e9s Newspaper [2020]. \u201cTwo of the four affected houses in Nicol\u00e1s Salmer\u00f3n are out of the confinement\u201d. (updated Oct 2025). https:\/\/www.eldiariomontanes.es\/cantabria\/salen-confinamiento-cuatro-20200715210923-ntvo.html"},{"issue":"5","key":"pone.0345041.ref011","doi-asserted-by":"crossref","first-page":"421","DOI":"10.1093\/oxfordjournals.aje.a112560","article-title":"Airborne spread of measles in a suburban elementary school","volume":"107","author":"EC Riley","year":"1978","journal-title":"Am J Epidemiol"},{"issue":"10","key":"pone.0345041.ref012","doi-asserted-by":"crossref","first-page":"1405","DOI":"10.1038\/s41588-021-00936-6","article-title":"The first wave of the COVID-19 epidemic in Spain was associated with early introductions and fast spread of a dominating genetic variant","volume":"53","author":"MG L\u00f3pez","year":"2021","journal-title":"Nat Genet"},{"key":"pone.0345041.ref013","unstructured":"National Center for Immunization and Respiratory Diseases (NCIRD), Division of Viral Diseases. CDC COVID-19 Science Briefs [Internet]. Atlanta (GA): Centers for Disease Control and Prevention (US); 2020\u20132023. Science Brief: SARS-CoV-2 and Surface (Fomite) Transmission for Indoor Community Environments. 2021 Apr 5. 34009771. (Updated Oct 2025). https:\/\/www.ncbi.nlm.nih.gov\/books\/NBK570437\/"},{"key":"pone.0345041.ref014","unstructured":"BOE [2020]. Bolet\u00edn Oficial del Estado: Real Decreto-ley 21\/2020, de 9 de junio, de medidas urgentes de prevenci\u00f3n, contenci\u00f3n y coordinaci\u00f3n para hacer frente a la crisis sanitaria ocasionada por el COVID-19. (updated Nov 2025). https:\/\/www.boe.es\/buscar\/doc.php?id=BOE-A-2020-5895"},{"issue":"6","key":"pone.0345041.ref015","doi-asserted-by":"crossref","first-page":"749","DOI":"10.1080\/10789669.2010.10390932","article-title":"Using CFD Capabilities of CONTAM 3.0 for Simulating Airflow and Contaminant Transport in and around Buildings","volume":"16","author":"LL Wang","year":"2010","journal-title":"HVAC&R Research"},{"issue":"9","key":"pone.0345041.ref016","doi-asserted-by":"crossref","first-page":"2350","DOI":"10.3390\/buildings13092350","article-title":"Multi-Zone Infection Risk Assessment Model of Airborne Virus Transmission on a Cruise Ship Using CONTAM","volume":"13","author":"Z Xia","year":"2023","journal-title":"Buildings"},{"key":"pone.0345041.ref017","doi-asserted-by":"crossref","first-page":"109184","DOI":"10.1016\/j.buildenv.2022.109184","article-title":"Evaluating SARS-CoV-2 airborne quanta transmission and exposure risk in a mechanically ventilated multizone office building","volume":"219","author":"S Yan","year":"2022","journal-title":"Build Environ"},{"issue":"1","key":"pone.0345041.ref018","doi-asserted-by":"crossref","first-page":"102","DOI":"10.3390\/buildings13010102","article-title":"Multizone Modeling of Airborne SARS-CoV-2 Quanta Transmission and Infection Mitigation Strategies in Office, Hotel, Retail, and School Buildings","volume":"13","author":"S Yan","year":"2022","journal-title":"Buildings"}],"updated-by":[{"DOI":"10.1371\/journal.pone.0354250","type":"correction","label":"Correction","source":"publisher","updated":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T00:00:00Z","timestamp":1784505600000}}],"container-title":["PLOS One"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0345041","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T17:41:50Z","timestamp":1778607710000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0345041"}},"subtitle":[],"editor":[{"given":"Baohua","family":"Wen","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2026,5,12]]},"references-count":18,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2026,5,12]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0345041","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,5,12]]}}}