Engineering control of respiratory infection and low-energy design of healthcare facilities

Indoor microorganisms and infection have become an emerging direction in indoor air quality research science. Airborne droplet nuclei can serve as carriers of respiratory infectious diseases. The study of expiratory droplets and their exposure control has received particular attention since the 2003 severe acute respiratory syndrome epidemics and the 2009 influenza pandemics. Little is known about how effective the commonly used indoor environment control strategies are for infection control. Significant questions also exist on the ventilation requirements for airborne infection control. There is a broad range of relevant important issues, including the exposure risk, and effective control methods in various indoor settings, such as hospitals, homes, schools, and offices. What is known is that the minimum required ventilation rate for infection control in hospitals can be much higher than the general health and comfort requirement in homes and offices. This has resulted in significant energy-efficiency issues in healthcare facilities. This review considers the current knowledge on airborne transmission of infection and the potential implications of a move to low-energy design, particularly in hospitals, on the risk of infection. The review outlines active research and development on reducing hospital energy use while improving infection control and discusses the potential for conducting "clinical trials" to gain the necessary evidence to support changes in hospital ventilation design.