1. A method of identifying individual aerosol particles in real time comprising: receiving sample aerosol particles; producing positive and negative test spectra of an individual aerosol particle using a bipolar single particle mass spectrometer; comparing each test spectrum to spectra of the same respective polarity in a database of predetermined positive and negative spectra for known particle types to obtain a set of substantially matching spectra; and determining the identity of the individual aerosol particle from the set of substantially matching spectra by determining a best matching one of the known particle types having both a substantially matching positive spectrum and a substantially matching negative spectrum associated therewith from the set.