The generation of airborne particles of biological origin generated in the breathing zone of medical and dental workers during various surface manipulations such as grinding and drilling have the potential to adversely impact the health of those exposed.   The characterization of airborne particles generated during a drilling process on animal bone with surface coated tools was recently conducted under controlled laboratory conditions.  The efficacy of a local exhaust ventilation (LEV) system with installed ultra low penetration air (ULPA) filters was evaluated for performance and particle removal efficiency.  Particles were monitored in the range of 0.02 micron to greater than 1 micron with both a portable laser particle counter and a condensation nuclei counter.  Future efforts involve the improvement of the particulate removal system through modifications in filter configurations and other pertinent parameters.  In addition, a performance predictive algorithm will developed for application as field and environmental conditions change.