Exposure of health care workers and occupants to coughed air in a hospital room with displacement air distribution: Impact of ventilation rate and distance from coughing patient

The exposure of a doctor and a second patient to coughed air by an infected patient was studied in a simulated two-bed hospital patient room ventilated at two air change rates (3 h^-1 and 6 h^-1). Thermal manikin with realistic body shape and surface temperature distribution was used as the doctor standing 0.55, 1.1 or 2.8 m downstream the cough. A coughing thermal dummy, lying in one bed and a second thermal manikin in the other bed (1.3 m away), were used as the "sick" and the "exposed" patients. The cough consisted of 100% CO₂. The doctor and the coughing patient faced each other. The highest Peak Concentration Level (PCL) for the doctor was at 6 h^-1, suggesting that the risk of airborne cross infection may increase when ventilation rate is increased. Displacement air distribution does not reduce the risk from crossinfection.