In particular, the complex entry in Annex IV of the CLP Regulation (EC) No 1272/2008 has caused uncertainty among many users: titanium dioxide powders and powdery mixtures containing more than 1 % titanium dioxide particles with an aerodynamic diameter not exceeding 10 micrometres are to be classified. Solid and liquid mixtures containing titanium dioxide are not to be classified but must be labelled with warnings under certain conditions. The aerodynamic diameter is a value that is more commonly known in connection with occupational health and safety regarding respirable particles: for example, the fine dust particle size classes for ...