With the speculated possible return of the Severe Acute Respiratory Syndrome (SARS), the next pandemic of influenza, and the current avian flu outbreak, there have been growing academic and public interests in understanding the environmental factors that cause transmission of infectious diseases as well as improving environmental control means in hospitals and the community at large. People stay most of their time indoors, and at the same time, the use of mechanical air-conditioning systems has been on the rise, in particular in developing countries such as China. Inadequate ventilation, excessive chemical release during renovation or decoration, poor commissioning and maintenance, as well as lack of understanding of the built environment by the residents are all significant issues in the built environment. The quality of built environment is closely associated with the occupant's heath, well-being, comfort and productivity. Research on built environments and health are of inter-disciplinary nature involving inputs from urban planning, building services, architecture, environmental engineering, microbiology, epidemiology, public health as well as decision makers. Inter-disciplinary collaboration is the key in improving built environment and thus public health in both developed and developing countries. Cooperation and communication across the boundaries between disciplines also benefit new technology development, policy implementation as well as technology transfer.