Breath-, air- and surface-borne SARS-CoV-2 in hospitals

Lian Zhou, Maosheng Yao, Xiang Zhang, Bicheng Hu, Xinyue Li, Haoxuan Chen, Lu Zhang, Yun Liu, Meng Du, Bochao Sun, Yunyu Jiang, Kai Zhou, Jie Hong, Na Yu, Zhen Ding, Yan Xu, Min Hu, Lidia Morawska, Sergey A. Grinshpun, Pratim BiswasRichard C. Flagan, Baoli Zhu, Wenqing Liu, Yuanhang Zhang

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


The COVID-19 pandemic has brought an unprecedented crisis to the global health sector. When discharging COVID-19 patients in accordance with throat or nasal swab protocols using RT-PCR, the potential risk of reintroducing the infection source to humans and the environment must be resolved. Here, 14 patients including 10 COVID-19 subjects were recruited; exhaled breath condensate (EBC), air samples and surface swabs were collected and analyzed for SARS-CoV-2 using reverse transcription-polymerase chain reaction (RT-PCR) in four hospitals with applied natural ventilation and disinfection practices in Wuhan. Here we discovered that 22.2% of COVID-19 patients (n = 9), who were ready for hospital discharge based on current guidelines, had SARS-CoV-2 in their exhaled breath (~105 RNA copies/m3). Although fewer surface swabs (3.1%, n = 318) tested positive, medical equipment such as face shield frequently contacted/used by healthcare workers and the work shift floor were contaminated by SARS-CoV-2 (3–8 viruses/cm2). Three of the air samples (n = 44) including those collected using a robot-assisted sampler were detected positive by a digital PCR with a concentration level of 9–219 viruses/m3. RT-PCR diagnosis using throat swab specimens had a failure rate of more than 22% in safely discharging COVID-19 patients who were otherwise still exhaling the SARS-CoV-2 by a rate of estimated ~1400 RNA copies per minute into the air. Direct surface contact might not represent a major transmission route, and lower positive rate of air sample (6.8%) was likely due to natural ventilation (1.6–3.3 m/s) and regular disinfection practices. While there is a critical need for strengthening hospital discharge standards in preventing re-emergence of COVID-19 spread, use of breath sample as a supplement specimen could further guard the hospital discharge to ensure the safety of the public and minimize the pandemic re-emergence risk.

Original languageEnglish (US)
Article number105693
JournalJournal of Aerosol Science
StatePublished - Feb 2021
Externally publishedYes


  • Airborne transmission
  • COVID-19
  • Exhaled breath
  • SARS-CoV-2
  • Surface-borne

ASJC Scopus subject areas

  • Environmental Engineering
  • Pollution
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes
  • Atmospheric Science


Dive into the research topics of 'Breath-, air- and surface-borne SARS-CoV-2 in hospitals'. Together they form a unique fingerprint.

Cite this