A Fluorescence Particle Spectrometer (FPS) performs real-time measurement of the fluorescence spectra of aerosol particles in the size range 1-10 m diameter. The FPS has a sufficiently high sample rate (estimated to be a few liters/min) to measure aerosol within buildings (from 1 up to 600 particle fluorescence spectra per minute) at practical rates. A virtual impactor first concentrates aerosol particles, which are then drawn under negative pressure through an aerodynamic focusing nozzle in the inlet of the instrument, through the sample region, providing further concentration. The rate of particle spectra measured by the FPS increases significantly when the particle inlet is within a few meters of some common sources of indoor biological particles.