AbstractThe tannin concentration of hard‐ and soft‐wood dust was determined in dust powder and in samples on filters. It varied from 1.6 ± 0.3 mg g−1(± SD) for fir, which is a soft wood, to 80 ± 30 mg g−1(± SD) for oak, which is a hard wood. The low detection limit of the spectrophotometric method (1.5 μg per sample) made the analysis possible with no interference from cellulose ester filters. In five woodworking shops the concentrations of the total dust varied from 0.2 to 20 mg m−3, while those of tannins varied from 2 to 341 μg m−3. As hard woods like oak or mahogany have a higher tannin concentration than soft woods, tannin concentration analysis in wood dust can be used as an indicator of exposure to hard‐wood dust.