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

Airborne wood dust poses health and safety risks in the construction and furniture industry. The study verified whether the thermal modification affects the share of fine wood dust particles (< 10 & mu;m) generated during spruce, oak, and meranti wood sanding. The experimental research involved nine material variants, including three wood species in three states: untreated, thermally modified at 160 & DEG;C, and thermally modified at 220 & DEG;C). To collect at least 200 g of each dust sample, a belt sander with P80 sandpaper and a belt speed of 10 m/s was used, along with a dust collector. The collected dust was then separated into fractions using a set of sieves with aperture sizes of 2000, 1000, 500, 250, and 125 & mu;m. A laser particle sizer was employed to measure the sizes of dust particles in the under-sieve fraction (dust with particle sizes smaller than 125 & mu;m). The under-sieve fraction was decomposed into three subfractions, with particle sizes: <2.5, 2.5-4.0, and 4.0-10 & mu;m. Surprisingly the results indicate that sanding dust from thermally modified wood generates a lower average mass share of potentially harmful fine particle fractions than dust from untreated wood. Oak dust contained a higher mass share of fine particles compared to the spruce and meranti dust samples. Dust from thermally modified oak and meranti wood had a lower content of harmful particle fractions than dust from untreated wood. The average mass shares of these dust fractions for modified wood at 160 and 220 & DEG;C showed no statictically significant differences (p < 0.05). Conversely, spruce dust had a low content of fine fractions because spruce particles exhibit a more irregular elongated shape. The study considered the extreme temperatures of 160 and 220 & DEG;C used in the thermal modification of wood. Therefore, the above statements are assumed to be valid for all intermediate thermo-modification temperatures.