Building Simulation

, Volume 11, Issue 5, pp 1039–1051 | Cite as

A simple method for differentiating direct and indirect exposure to exhaled contaminants in mechanically ventilated rooms

  • Chun ChenEmail author
  • Bin Zhao
  • Dayi Lai
  • Wei Liu
Research Article


Many airborne infectious diseases can be transmitted via exhaled contaminants transported in the air. Direct exposure occurs when the exhaled jet from the infected person directly enters the breathing zone of the target person. Indirect exposure occurs when the contaminants disperse in the room and are inhaled by the target person. This paper presents a simple method for differentiating the direct and indirect exposure to exhaled contaminants in mechanically ventilated rooms. Experimental data for 191 cases were collected from the literature. After analyzing the data, a simple method was developed to differentiate direct and indirect exposure in mixing and displacement ventilated rooms. The proposed method correctly differentiated direct and indirect exposure for 120 out of the 133 mixing ventilation cases and 47 out of the 58 displacement ventilation cases. Therefore, the proposed method is suitable for use at the early design stage to quickly assess whether there will be direct exposure to exhaled contaminants in a mechanically ventilated room.


ventilation non-isothermal jet particles droplets indoor environment 


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This work was supported by the National Natural Science Foundation of China (No. 51708474).


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Copyright information

© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Mechanical and Automation EngineeringThe Chinese University of Hong Kong, ShatinHong KongChina
  2. 2.Shenzhen Research InstituteThe Chinese University of Hong KongShenzhenChina
  3. 3.Department of Building Science, School of ArchitectureTsinghua UniversityBeijingChina
  4. 4.Beijing Key Laboratory of Indoor Air Quality Evaluation and ControlTsinghua UniversityBeijingChina
  5. 5.Tianjin Key Lab of Indoor Air Environmental Quality Control, School of Environmental Science and EngineeringTianjin UniversityTianjinChina
  6. 6.School of Civil Engineering, ZJU-UIUCZhejiang UniversityHainingChina

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