Particle size analysis of airborne wood dust produced from sawing thermally modified wood

Thermal modification imparts desirable properties in wood, including increased dimensional stability and greater resistance to fungal decay. While there is a substantial amount of performance data for thermally modified wood, there is little data available regarding the airborne particle size distribution of dust produced when processing thermally modified wood using standard machining equipment. Therefore, utilizing a Micro-Orifice Uniform Deposit Impactor, this research analyzed the size distribution of airborne particles produced when processing 170 °C thermally modified yellow poplar, red maple, white ash, aspen, and balsam fir on an industrial table saw. Ultimately, the aim of this research was to provide preliminary data that may assist wood products industry manufacturers and environmental health and safety officials in identifying potential hazards of airborne thermally modified wood dust. The study revealed slight differences in airborne particulate matter (PM) by wood species. The unmodified yellow poplar, red maple, and white ash all had relatively similar amounts of PM₁₀ (~ 29%), while balsam fir (~ 10%) had the least amount. The unmodified yellow poplar also had the highest amount of PM_2.5 and PM₁, 14% and 10%, respectively, while the balsam fir had the least amount of PM_2.5 and PM₁, 2.00% and 1.45%, respectively. Thermally modified yellow poplar had the highest PM₁₀, PM_2.5, and PM₁. Statistical analysis revealed that none of the five wood species had a significant difference (p < 0.05) in particle size distribution between unmodified and thermally modified forms.