Size and shape of airborne dust from wood sanding I. Size and shape index distributions of airborne dust

To characterize size, shape, and their distributions of airborne sanding du st particles of Japanese beech, geometric sizes and shape indices of freely faling particles collected on glass plates during and after sanding were a nalyzed by an image analyzer, Heywood diameter, maximum length, and maximum breadth were the geometric sizes, and circularity, slenderness ratio, and area sufficiency were the shape indices measured. Fequencies and cumulative undersizes of the particles were calculated for various geometric sizes an d shape indices, and the data were fitted to normal, log-normal, and Weibul l distributions. Furthermore, several characteristic values of the distribu tions were calculated. Changes in the particle sizes, shapes, and their dis tributions with time were also investigated. The results were summarized as follows: (1) Heywood diameter, maximum length, maximum breadth, and circularity dist ributions of airborne dust particles could be expressed by Weibull distribu tions, and slenderness ratio, and area sufficiency distributions could be e xpressed by log-normal distributions regardless of sanding conditions and t iming of dust particle sampling. (2) The particles were mostly slender, and had an uneven circumference. Max imum length, maximum breadth, and Heywood diameter of the particles were ab out 38-46, 23-28, 23-28 mum, respectively. (3) Particles collected after sanding were smaller and more circular than p articles collected during sanding.