Effect of Microbial Contamination of Water-Based Metalworking Fluids on the Aerosolization of Particles and Microbial Fragments

Aerosolization of particles from metalworking fluids (MWFs) was studied using a laboratory-scale set-up that simulates grinding operations. Semi-synthetic MWF and soluble oil were contaminated with Pseudomonas fluorescens, and the aerosolized particles were measured using a photometric mass monitor, optical particle counter, and a condensation nucleus counter. Microbial contamination of both semi-synthetic MWF and soluble oil increased the mass concentration as measured by the photometric aerosol mass monitor and the fine particle number concentration as measured by the condensation nucleus counter. These effects were seen most clearly for the fine size range of particles aerosolized from contaminated semi-synthetic MWF. Endotoxin results indicate that the increase in the fine particle concentration occurs at least partially due to the increase in the microbial cell wall components (fragments).