Physical factors that affect microbial transfer during surface touch

Zhao, Pengcheng; Chan, Peter S.; YuShi, Gao; Lai, Hon-Wai; Zhang, Tong; Li, Yuguo

doi:10.1016/j.buildenv.2019.05.005

Cited by 34 publications

(42 citation statements)

References 41 publications

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“…In this context, it is known that there is generally a higher surfacetouch transfer rate from smooth to rough surfaces, and most toilet surfaces are made to be smooth . 13 We failed to detect any viruses on non-toilet object surfaces in the patients' rooms, unlike in a 2020 study by Ong et al, 11 who detected 13/15 (87%) positive samples in one patient's room, and 3/5 (60%) in toilet sites, although anteroom and corridor samples were negative. It is interesting that the patient in their study had no pneumonia or diarrhoea, but that his/her stool samples were positive for SARS-CoV-2.…”

Section: Discussioncontrasting

confidence: 70%

Toilets dominate environmental detection of SARS-CoV-2 virus in a hospital

Zhang

Qian

et al. 2020

Preprint

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words)Main text (3372 words) AbstractBackground: Respiratory and faecal aerosols play a suspected role in transmitting the SARS-CoV-2 virus. We performed extensive environmental sampling in a dedicated hospital building for Covid-19 patients in both toilet and non-toilet environments, and analysed the associated environmental factors. Methods:We collected data of the Covid-19 patients. 107 surface samples, 46 air samples, two exhaled condensate samples, and two expired air samples were collected were collected within and beyond the four three-bed isolation rooms. We reviewed the environmental design of the building and the cleaning routines. We conducted field measurement of airflow and CO2 concentrations. Findings:The 107 surface samples comprised 37 from toilets, 34 from other surfaces in isolation rooms (ventilated at 30-60 L/s), and 36 from other surfaces outside isolation rooms in the hospital. Four of these samples were positive, namely two ward door-handles, one bathroom toilet-seat cover and one bathroom door-handle; and three were weakly positive, namely one bathroom toilet seat, one bathroom washbasin tap lever and one bathroom ceiling-exhaust louvre. One of the 46 air samples was weakly positive, and this was a corridor air sample. The two exhaled condensate samples and the two expired air samples were negative.Interpretation: The faecal-derived aerosols in patients' toilets contained most of the detected SARS-CoV-2 virus in the hospital, highlighting the importance of surface and hand hygiene for intervention.

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Section: Discussioncontrasting

confidence: 70%

Toilets dominate environmental detection of SARS-CoV-2 virus in a hospital

Zhang

Qian

et al. 2020

Preprint

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“…Additionally, the surface material or finish inside a toilet may allow a better transfer during swab-sampling than the other sampled surfaces. In this context, there is generally a higher surface-touch transfer rate from smooth to rough surfaces, and most toilet surfaces are made to be smooth ( Zhao et al, 2019 ). No virus was detected on non-toilet object surfaces in the patients' rooms, in contrast to a 2020 study by Ong et al (2020) wherein 13 of 15 (87%) samples in one patient's room and three of five (60%) toilet sites were positive, although anteroom and corridor samples were negative.…”

Section: Resultsmentioning

confidence: 99%

Toilets dominate environmental detection of severe acute respiratory syndrome coronavirus 2 in a hospital

Zhang

Qian

et al. 2021

Science of The Total Environment

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Respiratory and fecal aerosols play confirmed and suspected roles, respectively, in transmitting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). An extensive environmental sampling campaign of both toilet and non-toilet environments was performed in a dedicated hospital building for patients with coronavirus disease 2019 (COVID-19), and the associated environmental factors were analyzed. In total, 107 surface samples, 46 air samples, two exhaled condensate samples, and two expired air samples were collected within and beyond four three-bed isolation rooms. The data of the COVID-19 patients were collected. The building environmental design and the cleaning routines were reviewed. Field measurements of airflow and CO 2 concentrations were conducted. The 107 surface samples comprised 37 from toilets, 34 from other surfaces in isolation rooms, and 36 from other surfaces outside the isolation rooms in the hospital. Four of these samples were positive, namely two ward door handles, one bathroom toilet seat cover, and one bathroom door handle. Three were weakly positive, namely one bathroom toilet seat, one bathroom washbasin tap lever, and one bathroom ceiling exhaust louver. Of the 46 air samples, one collected from a corridor was weakly positive. The two exhaled condensate samples and the two expired air samples were negative. The fecal-derived aerosols in patients' toilets contained most of the detected SARS-CoV-2 in the hospital, highlighting the importance of surface and hand hygiene for intervention.

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“…To complete the transmission cycle, we need, finally, to consider surface-to-surface transfer. 46 Many recent studies have measured the transfer of a variety of bacteria and viruses between fomites and hands or cleaning cloths (see Zhao et al 86 and references therein). Of the wide range of environmental factors studied, a few have very strong effects, e.g., for some bacteriophages, humidity increases the rate of surface-to-hand transfer approximately threefold, 87 perhaps pointing to a role for capillarity.…”

Section: Perspective Soft Mattermentioning

confidence: 99%

“…Surface roughness and porosity, the contact force, the direction of transfer (hand to surface or vice versa), and the type of microorganism are all also significant. 86 Studies to date of the transference of particulate matter between surfaces have been largely empirical, producing parameters such as the transference efficiency between different types of surfaces [88][89][90] as inputs for numerical modelling of the transference process. 90 There are therefore significant opportunities for soft matter science to contribute towards determining the mechanistic basis of surface to surface transfer.…”

Section: Perspective Soft Mattermentioning

confidence: 99%