Assessment of displacement ventilation systems in airborne infection risk in hospital rooms

• Published in: PloS one 2019-01, Vol.14 (1), p.e0211390
• Main Authors: Villafruela, José Manuel, Olmedo, Inés, Berlanga, Félix A, Ruiz de Adana, Manuel
• Format: Article
• Language: English
• Subjects: Air Filters - standards; Air flow; Air leakage; Air Movements; Air Pollutants - adverse effects; Air pollution; Air Pollution, Indoor - adverse effects; Air Pollution, Indoor - analysis; Air Pollution, Indoor - prevention & control; Airborne infection; Airborne infections; Airflow; Analysis; Biology and Life Sciences; Breathing; Computer simulation; Contaminant dispersion; Contaminants; Cross infection; Design; Disease Transmission, Infectious - prevention & control; Displacement; Ecology and Environmental Sciences; Energy conservation; Energy consumption; Exposure; External walls; Flow (Dynamics); Flow pattern; Health care; Health risk assessment; Health risks; Heat; Hospital patients; Hospitals; Hospitals - standards; Hospitals - statistics & numerical data; Humans; Infection; Infections; Inhalation; Inhalation Exposure - adverse effects; Inhalation Exposure - prevention & control; Mathematical models; Medicine and Health Sciences; Nosocomial infections; Numerical analysis; Numerical models; Numerical simulations; Occupational exposure; Pathogenic microorganisms; Pathogens; Physical chemistry; Physical Sciences; Pollutant removal; Pollutants; Radiation (Physics); Respiration; Risk; Risk factors; Solar radiation; Three dimensional models; Ventilation; Ventilation - methods; Ventilation equipment
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0211390

Efficient ventilation in hospital airborne isolation rooms is important vis-à-vis decreasing the risk of cross infection and reducing energy consumption. This paper analyses the suitability of using a displacement ventilation strategy in airborne infection isolation rooms, focusing on health care worker exposure to pathogens exhaled by infected patients. The analysis is mainly based on numerical simulation results obtained with the support of a 3-D transient numerical model validated using experimental data. A thermal breathing manikin lying on a bed represents the source patient and another thermal breathing manikin represents the exposed individual standing beside the bed and facing the patient. A radiant wall represents an external wall exposed to solar radiation. The air change efficiency index and contaminant removal effectiveness indices and inhalation by the health care worker of contaminants exhaled by the patient are considered in a typical airborne infection isolation room set up with three air renewal rates (6 h-1, 9 h-1 and 12 h-1), two exhaust opening positions and two health care worker positions. Results show that the radiant wall significantly affects the air flow pattern and contaminant dispersion. The lockup phenomenon occurs at the inhalation height of the standing manikin. Displacement ventilation renews the air of the airborne isolation room and eliminates the exhaled pollutants efficiently, but is at a disadvantage compared to other ventilation strategies when the risk of exposure is taken into account.