Dispersion of exhaled droplet nuclei in a two-bed hospital ward with three different ventilation systems

H. Qian, Y. Li, Peter V. Nielsen, Carl-Erik Hyldgård, T. Wai Wong, A.T.Y. Chwang

Research output: Contribution to journalJournal articleResearchpeer-review

145 Citations (Scopus)

Abstract

Effective ventilation in general hospital wards is important for controlling the airborne transmission of infectious respiratory diseases. Experiments have been carried out to increase our understanding of the interaction of the breathing flows of two individuals in a full-scale experimental hospital ward with three ventilation systems, i.e. mixing, downward and displacement ventilation. Two life-size breathing thermal manikins were used to simulate a source patient and a receiving patient. The exhalation jet from a bed-lying manikin was visualized using smoke. N2O was used as tracer gas to simulate the droplet nuclei exhaled by patients; and the spatial distribution of its concentrations was measured. Our experimental results show that for both mixing and downward ventilation, the exhaled jet penetrates a short distance and is diluted quickly by ventilation air. The exhaled droplet nuclei are well mixed in the ward. Bed distance does not affect the personal exposure of the receiving patient. For displacement ventilation, the exhaled jet can penetrate a long distance. A high concentration layer of exhaled droplet nuclei because of thermal stratification locking has also been observed with displacement ventilation. This work is useful for identifying an appropriate ventilation method that can remove droplet nuclei more effectively and minimize the risk of cross-infections in a hospital ward environment.

Original languageEnglish
JournalIndoor Air
Volume16
Issue number2
Pages (from-to)111-128
Number of pages18
ISSN0905-6947
DOIs
Publication statusPublished - 2006

Fingerprint

Hospital beds
Ventilation
Manikins
Respiration
Hot Temperature
Exhalation
Thermal stratification
Patients' Rooms
Pulmonary diseases
Infectious Disease Transmission
Cross Infection
Smoke
General Hospitals
Spatial distribution
Gases
Air

Keywords

  • Ventilation systems
  • Infection control
  • Air distribution
  • Hospital ventilation
  • Airborne transmission
  • Exhalation jet
  • Flow visualization

Cite this

Qian, H. ; Li, Y. ; Nielsen, Peter V. ; Hyldgård, Carl-Erik ; Wai Wong, T. ; Chwang, A.T.Y. / Dispersion of exhaled droplet nuclei in a two-bed hospital ward with three different ventilation systems. In: Indoor Air. 2006 ; Vol. 16, No. 2. pp. 111-128.
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Dispersion of exhaled droplet nuclei in a two-bed hospital ward with three different ventilation systems. / Qian, H.; Li, Y.; Nielsen, Peter V.; Hyldgård, Carl-Erik; Wai Wong, T.; Chwang, A.T.Y.

In: Indoor Air, Vol. 16, No. 2, 2006, p. 111-128.

Research output: Contribution to journalJournal articleResearchpeer-review

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AU - Chwang, A.T.Y.

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