Fine dust after sanding untreated and thermally modified spruce, oak, and meranti wood

Abstract

Abstract Airborne wood dust causes health and safety hazards in the construction and furniture industry. The study verified whether the thermal modification affects the share of the finest wood dust particles (< 10 μm) created by sanding oak, spruce, and meranti wood. The experimental research included nine variants of materials (three species of wood in three states: untreated, thermally modified at 160°C, and thermally modified at 220°C). A belt sander with a dust collector allowed the collection of at least 200 g of each dust variant (P80 sandpaper and 10 m/s belt speed). Next, a set of sieves with 2000, 1000, 500, 250, and 125 µm aperture sizes was used to recognize the gradation of the wood particle aggregate. A laser particle sizer was used to determine details of dust with particle sizes smaller than 125 μm. The size distribution of the finest particles was analyzed in four fractions with particle sizes < 2.5, 2.5-4, and 4-10 μm. The results show that, surprisingly, sanding dust from thermally modified wood generates a lower average mass share of potentially harmful particle fractions than dust from untreated wood. When comparing tested wood species, it is noticed that oak dust has a higher proportion of the best particles than spruce and Meranti dust. Dust from thermally modified oak and meranti has a lower content of harmful particle fractions than dust from untreated wood. The average mass shares of these dust fractions formed during the sanding of modified wood at 160 and 220°C are not significantly different (p <0.05). The opposite was observed in the case of spruce wood because spruce dust has a low content of fine fractions, and its particles have a more irregular elongated shape. The study took into account the extreme temperatures used in the thermal modification of wood (160 and 220°C), then it can be assumed that the statements mentioned above are valid in all intermediate thermos-modification temperatures.