Development of ventilation design strategy for effective removal of pollutant in the isolation room of a hospital

This paper investigates the airflow and pollutant distribution patterns in a "negative pressure" isolation room by means of objective measurement and computational fluid dynamics (CFD) modeling based on three ventilation strategies. An effective ventilation system is crucial to protect doctors, nurses and other health-care workers from patients with infectious disease. In the preliminary study with Strategy 1, the isolation room has two air supply diffusers and two extract grilles mounted on the ceiling. Strategy 2 retains the air supply diffusers in Strategy I but relocates the two extract grilles to the wall behind the bed at 0.3 m above the floor level. Strategy 3 has the same layout as Strategy 2 except the ceiling diffusers are replaced by supply grilles and relocated closer to the wall behind the bed. The results show that the low-level extraction technique adopted in Strategies 2 and 3 is very effective in removing pollutant at the human breathing zone as compared to extraction at ceiling level in Strategy 1. It is found that Strategy 3 has the best pollutant removal efficiency with the supply air grilles delivering a laminar flow of outside air to the occupant with minimal entrainment of the air in the room. It is observed that the ventilation strategies and furniture layout have great influence on the airflow and pollutant distribution patterns in the isolation room. Design strategies of isolation room are formulated based on the results and observations made in this study. (C) 2005 Elsevier Ltd. All rights reserved.