This report describes a study in which a nano aerosol mass spectrometer (NAMS) was used to study composition of nanoparticles in real time near a major roadway intersection. Dr. Murray V. Johnston of the University of Delaware, Newark, and colleagues conducted a field test in Wilmington, Delaware, to evaluate performance of the instrument in a real-world setting and to assess whether it could aid in identifying the major source contributions to nanoparticle spikes and background levels, including distinguishing diesel from gasoline vehicles.
