A simple method for differentiating direct and indirect exposure to exhaled contaminants in mechanically ventilated rooms
- 42 Downloads
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.
Keywordsventilation non-isothermal jet particles droplets indoor environment
Unable to display preview. Download preview PDF.
This work was supported by the National Natural Science Foundation of China (No. 51708474).
- Baturin VV (1972). Fundamentals of Industrial Ventilation. Oxford, UK: Pergamon Press. pp. 79–119.Google Scholar
- Bloch AB, Orenstein WA, Ewing WM, Spain WH, Mallison GF, Herrmann KL, Hinman AR (1985). Measles outbreak in a pediatric practice: Airborne transmission in an office setting. Pediatrics, 75: 676–683.Google Scholar
- Bocksell T (1998). An enhanced DRW model for turbulent particle diffusion. Master Thesis, University of Illinois at Urbana-Champaign, USA.Google Scholar
- Li X, Niu J, Gao N (2012). Co-occupant’s exposure of expiratory droplets—Effects of mouth coverings. HVAC&R Research, 18: 575–587.Google Scholar
- Nielsen PV, Zajas J, Litewnicki M, Jensen RL (2014). Breathing and cross-infection risk in the microenvironment around people. In: Proceedings of ASHRAE Winter Conference, NY-14-C020, New York, USA.Google Scholar
- OSHA (2014). OSHA Technical Manual (OTM). Section II: Chapter 1, Personal sampling for air contaminants. Occupational Safety & Health Administration Available at https://www.osha.gov/dts/osta/otm/otm_ii/pdfs/otmii_chpt1_allinone.pdf. Accessed 17 Oct 17 2014.