Separate determination of PM10 emission factors of road traffic for tailpipe emissions and emissions from abrasion and resuspension processes

Little is known about the relevance of mechanically produced particles of road traffic from abrasion and resuspension processes in relation to the exhaust pipe particles. In this paper emission factors of PM10 and PM1 for light and heavy-duty vehicles were derived for different representative traffic regimes from concentration differences of particles and nitrogen oxides (NOx) in ambient air upwind and downwind of busy roads, or alternatively of kerbsides and nearby background sites. Hereby PM1 was interpreted as direct exhaust emissions and PM10-PM1 as mechanically produced emissions from abrasion and resuspension processes. The results show that abrasion and resuspension processes represent a significant part of the total primary PM10 emissions of road traffic. At sites with relatively undisturbed traffic flow they are in the same range as the exhaust pipe emissions. At sites with disturbed traffic flow due to traffic lights emissions from abrasion/resuspension are even higher than those from the exhaust pipes.