The finest particles in dust after sanding untreated and thermally modified spruce, oak and meranti wood

Abstract Airborne wood dust causes health and safety hazards in the construction and furniture industry. The research verified whether the thermal modification affects the share of the finest dust particles, smaller than < 10 µm, in the wood dust. The experimental research included nine variants of materials (untreated and thermally modified – in 160°C by 3 h and in 220°C by 3 h – oak, spruce, and meranti wood). The dust was generated with a belt sander (P120 sandpaper, 14.5 m/s belt speed, and 0.65 N/cm2 pressure). The four fractions with particle sizes  250 µm, were assessed with sieves with aperture sizes of 25, 80, and 250 µm. The content and size distribution of the finest particles in the fractions were measured with laser particle sizer. The results suggest that: (1) both untreated and thermally modified oak wood dust show the higher share of the finest particles in comparison to spruce and meranti wood. (2) Dust from thermally modified oak and meranti has a lower content of harmful particle fractions than dust from untreated wood. The opposite was observed in the case with spruce wood because spruce dust has a low content of fine fractions and its particles have a more irregular elongated shape. (3) 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 two statements mentioned above are valid in all intermediate temperatures.