Identification of the physical and chemical characteristics of particulate matter (PM) to determine its toxicity could facilitate targeted abatement policies and more effective control measures to reduce the burden of disease due to air pollution. AWHO workshop evaluated the progress in research on this important issue. The participants concluded that current knowledge does not allow specific quantification of the health effects of emissions from different sources or of individual PM components. It is therefore appropriate that current risk assessment practices consider particles of different sizes, from different sources and with different composition, as equally hazardous to health. The available evidence on the hazardous nature of combustion-related PM (from both mobile and stationary sources), however, is more consistent than for PM from other sources. Better understanding of the role of various characteristics of PM will require better characterization of the population exposure to the source-specific pollution, as well as improvement and widening of the scope of health outcomes studied.

Report on World Health Organizaton workshop Bonn, Germany 26-27 March 2007