AEROSOL EMISSION IN A ROAD TUNNEL

Continuous measurements of aerosol emissions were performed within the scope of emission measurements in the Gubrist tunnel a 3250 m long fr eeway,tunnel near Zurich, Switzerland, from 20 September to 26 Septemb er 1993. The particles in the respirable size range (d < 3 mu m) were found to be mainly tail pipe emissions with very small amount of tire wear and road dust. The calculated PM(3) emission factor for diesel en gines was about 310 mg km(-1), where the main part (63%) of the diesel vehicles were heavy-duty vehicles. Thirty-one percent of the PM(3) em issions from diesel Vehicles were black carbon and 0.86% particle boun d PAH. Due to the high fraction emitted by diesel engines the contribu tion of gasoline engines could not be evaluated by the statistical mod el. During, their residence time in the tunnel the particles undergo s ignificant changes, resulting in a more compact structure. It is concl uded that this is mainly due to adsorption of Volatile material from t he gas phase to the particle surface. Copyright (C) 1996 Elsevier Scie nce Ltd