The environmental pollution associated with electrical discharge machining is not yet clearly understood. Airborne exposure to nanoscale and respirable particles were investigated with regard to the aerosol characteristics of a wire electrical discharge machining (WEDM) workshop. The total number concentration of the aerosol was multimodal, with the highest peak maxima during the working hours of 10:00 am and 3:00 pm. The majority of the released particles were smaller than d = 100 nm, with the maximum amount sized 40 nm. A large quantity of metallic elements, including Fe, Al and Cu, were found in the aerosol particulates coming from WEDM processing. Furthermore, the aerosol particles exhibited higher cellular toxicity and ROS producing ability in human alveolar epithelial cells (16HBE) when compared to the atmospheric background. Our results indicate substantial hazards arising from exposure to polluted atmosphere of a WEDM workshop. Effective exposure controls and protections are thus strongly recommended.