Human exposure to traffic pollution. Experience from Danish studies

Air pollution may have severe long-term as well as short-term health effect s. The determination of possible links between pollution levels and impact on human health is, however, not a straightforward task. A key problem is t he assessment of human exposure to ambient pollution levels. In later years , the possible role of particulate pollution as a health hazard has drawn m ajor attention and is, therefore, the subject of research projects in many countries including Denmark. The present paper fives a review of recent and ongoing/planned Danish air pollution exposure studies. Furthermore, key re sults from Banish studies of ultrafine particles from urban traffic are out lined. The exposure studies show that air pollution models may be strong to ols in impact assessment studies, especially when used in combination with personal exposure monitoring and application of biomarkers. Personal exposu re measurements in Copenhagen indicate that indoor pollution levels may be very important for the personal exposure to fine fraction particles (PM2.5) . Measurements with a differential mobility analyzer (DMA) in Danish urban areas show that number concentrations of ultrafine particles (<100 nm) in b usy streets are strongly correlated with classic traffic pollutants such as nitrogen oxides and carbon monoxide. The number concentrations in urban Da nish streets have decreased considerably between two campaigns in 1999 and 2000, apparently as a result of reductions in sulfur contents in Danish die sel fuels that took place in July 1999.