A Comparative Study of Urban Road Dust to Airborne Particles in Freiburg, Germany




Professor and Department Chair

Project Summary

The Penn Undergraduate Climate Action Grant funded my summer research trip to Freiburg, Germany, where I collaborated with one of Dr. Gieré’s colleagues, Dr. Volker Dietze at the German Meteorological Service. The Meteorological Service’s Particle Laboratory collects ambient air samples worldwide using passive sampler technology. These routine measurements of natural and anthropogenic particles are used to determine air quality and pollution levels.  Information, including particle size and shape, as well as mass concentration, can be determined using automated transmitted light microscopy (TLM). 

Road dust is composed of natural and anthropogenic particles accumulated on the street surface.  Natural particles usually originate from soils and bedrock, whereas the anthropogenic components are introduced by industrial activities, combustion processes, traffic, and mechanical wear. During this study, I focused on the 2.5–80 µm size fraction of road dust. Particles within this size can be mobilized by disruptions, such as passing vehicles and wind, thus increasing the likelihood of interaction with humans by ingestion, inhalation, or epidermal contact. Therefore, this size range is a potential human health hazard. The smaller the particle, the deeper it can penetrate the human respiratory system if inhaled.

The town of Freiburg, Germany only permits vehicle and truck traffic around its outer rim.  Pedestrians, bikers, and public transportation share the streets of the inner city during the day.  Sites were selected with varying traffic volume and type in order to see its impact on the deposited road dust. Samples were collected across the entire road surface with a cyclone vacuum. The area sampled per lane of traffic averaged six meters squared. Ambient particle samples were taken over seven days using the Meteorological Service’s passive samplers, which are mounted at 1.5m above the street surface in specific locations.

A Comparative Study of Urban Road Dust to Airborne Particles in Freiburg, Germany