Severe acute respiratory syndrome and biology, air quality, physics, and mechanical engineering.

The US Centers for Disease Control and Prevention state that the primary way that severe acute respiratory syndrome (SARS) appears to be spread is by close person-to-person contact, and contact with infectious droplets. They further state that it is also possible that SARS could be spread more broadly through the air, or by other means currently not known. The possibility of non-droplet transmission as a means of spread has been voiced previously by Ronald Atlas, the President of the American Society of Microbiology. Commenting on the Metropole Hotel outbreak he stated this would suggest “that it spread through the air-conditioning system”. This was also echoed at two recent multidisciplinary, local meetings where speakers were predominantly non-medical scientists from the Hong Kong University of Science and Technology (HKUST). Call was made not to neglect the possibility of the airborne mode of spread in future research on SARS transmission. Concern was raised regarding the current paradox of advocating improvement of indoor ventilation at medical facilities, which helps to control airborne infection, but not droplet spread. This commentary, based largely on these nonmedical scientists’ perspectives on SARS, illustrates the abundance of local scientific expertise available and the eagerness of these scientists to assist in the understanding of the SARS outbreak.