1 Chemical and physical characterization of traffic particles in 2 four different highway environments in the Helsinki 3 metropolitan area 4 5 J. Enroth1,2, S.Saarikoski3, J.V. Niemi4,5, A. Kousa4, I. Ježek6, G. Močnik6,7, S. 6 Carbone3,9, H. Kuuluvainen8, T. Rönkkö8, R. Hillamo3, and L. Pirjola1,2,* 7 8 [1] {Metropolia University of Applied Sciences, Department of Technology, Helsinki, Finland} 9 [2] {University of Helsinki, Department of Physics, Helsinki, Finland} 10 [3] {Finnish Meteorological Institute, Atmospheric Composition Research, Helsinki, Finland} 11 [4] {Helsinki Region Environmental Services Authority HSY, Helsinki, Finland} 12 [5] {University of Helsinki, Department of Environmental Sciences, Helsinki, Finland} 13 [6] {Aerosol d.o.o., Ljubljana, Slovenia} 14 [7] {Jožef Stefan Institute, Ljubljana, Slovenia} 15 [8] {Tampere University of Technology, Department of Physics, Tampere, Finland} 16 [9] {now at University of São Paulo, Department of Applied Physics, São Paulo, Brazil} 17 18 Correspondence to: L. Pirjola (
[email protected],
[email protected]) 19 20 1 1 Abstract 2 Traffic related pollution is a major concern in urban areas due to its deleterious effects on human 3 health. The characteristics of the traffic emissions on four highway environments in the Helsinki 4 metropolitan area were measured with a mobile laboratory, equipped with state-of-the-art 5 instrumentation. Concentration gradients were observed for all traffic related pollutants, 6 particle number (CN), particulate mass PM1, black carbon (BC), organics and nitrogen oxides 7 (NO and NO2). Flow dynamics in different environments appeared to be an important factor 8 for the dilution of the pollutants.