Reduction of Airborne Dust Generated from Circular Sawing by Providing Water to Work Pieces

Our previous study showed that airborne dust mass was less in sawing high moisture content lumber than dried lumber. Based on this finding, we developed the technique of reducing airborne dust generated from circular sawing by applying water to work pieces before sawing. Boards of air-dried sugi (Cryptomeria japonica) were soaked in water for 1 or 3 days, or had their top surfaces wetted using a roller containing water before circular sawing. The mass concentration of airborne dust (of 10 mu m or less diameter) generated from circular sawing was measured with a low volume air sampler at a point 1550 mm above the floor and at 600 mm from the axis of the circular saw toward an operator. Soaking for 1 day decreased the mass concentration to about one-half of that in sawing air-dried lumber and to about one-third of that for 3 days of soaking. Soaking in water is effective for reducing airborne dust mass concentration. Wetting lumber surfaces decreased the mass concentration to about one-half. In this case, the sawdust generated was attached to the top surface (wetted surface) of work pieces, and thus the mass concentration was reduced. These findings suggested that the mass concentration of airborne dust generated from circular sawing could be reduced by soaking work pieces into water or by wetting the top surface of work pieces using a water-soaked roller.