Abstract: For over a decade, mass spectrometry has been used to determine the chemical composition of individual airborne particles. It has been coupled with various size measurement or size selection methods to provide correlated size-composition information of ambient aerosols. Our emphasis has been on the analysis of particles in the 10-200 nm diameter range. This size range is important because of its link to adverse health effects. These particles are hard to characterize since they are too small to be detected and sized by conventional light scattering methods. Correlated size-composition information is obtained by sampling the aerosol with a size-selective inlet and ablating individual particles on-the-fly with a pulsed laser. This approach has been used to obtain size-resolved single particle mass spectra from hundreds of thousands of ambient ultrafine particles at several urban sampling sites.
In this talk, the methodology for sampling and analysis of ultrafine particles will be reviewed and ambient particle data from the Baltimore supersite will be presented. The Baltimore aerosol is a cacophony of organic, inorganic and metal constituents. What we breathe in depends strongly on the time of day and meteorological variables such as temperature, relative humidity and wind direction.