Definitions and relation of airborne wood dust fractions

European Directive 2004/37/EC, which recommends limit values for workers exposure to inhalable fraction of hardwood dust, has been fully accepted in Croatia in 2007. Prior regulation has recommended the limit values for respirable particles and „total dust“. The researches of workers’ exposure to wood dust at their workplace in countries throughout the world used to determine mass concentrations of „total dust“. Due to a significant number of already existing data on exposure, in recent ten years the aim of researches in European countries has been to find conversion ratio for mass concentration of „total dust“ to mass concentration of inhalable fraction. Recommended conversion factors enable the comparison between 234 mass concentrations of „total dust“ of hardwood species, obtained so far in researches of workers’ exposure in Croatia, with current limit value for inhalable fraction. The results of comparison are troublesome. Side-by-side determination of workers exposure to “total dust” and inhalable fraction should be conducted.