Role of ventilation in airborne transmission of infectious agents in the built environment - a multidisciplinary systematic review

There have been few recent studies demonstrating a definitive association between the transmission of airborne infections and the ventilation of buildings. The severe acute respiratory syndrome (SARS) epidemic in 2003 and current concerns about the risk of an avian influenza (H5N1) pandemic, have made a review of this area timely. We searched the major literature databases between 1960 and 2005, and then screened titles and abstracts, and finally selected 40 original studies based on a set of criteria. We established a review panel comprising medical and engineering experts in the fields of microbiology, medicine, epidemiology, indoor air quality, building ventilation, etc. Most panel members had experience with research into the 2003 SARS epidemic. The panel systematically assessed 40 original studies through both individual assessment and a 2-day face-to-face consensus meeting. Ten of 40 studies reviewed were considered to be conclusive with regard to the association between building ventilation and the transmission of airborne infection. There is strong and sufficient evidence to demonstrate the association between ventilation, air movements in buildings and the transmission/spread of infectious diseases such as measles, tuberculosis, chickenpox, influenza, smallpox and SARS. There is insufficient data to specify and quantify the minimum ventilation requirements in hospitals, schools, offices, homes and isolation rooms in relation to spread of infectious diseases via the airborne route. © 2007 The Authors Journal compilation 2007 Blackwell Munksgaard

Geomorphic classification of rivers and streams

deuxième éditionInternational audienceThis chapter discusses general philosophies of classifications in fluvial geomorphology, and reviews examples of geomorphic classification systems. It explores uses and limitations of classifications as a tool in fluvial geomorphology and river management. Buffington and Montgomery emphasize the distinction between descriptive and process‐based classifications, noting that descriptive classifications can be quantitative and process‐based classifications can be qualitative. Distinctions between mountain torrents and lowland rivers are perhaps the oldest form of river classification. A wide range of geomorphic river classification schemes have been proposed since the late 19th century, reflecting the diversity of environmental settings, the variety of potential approaches to ordering complex natural systems, the intellectual framework of the field and the diverse purposes for which the systems were developed. Classification can focus on spatial features such as river patterns, floodplains, in‐channel features, which can be separated according to a set of parameter