Preliminary Maximum Permissible Concentrations (MPC's) in air are derived for 46 volatile compounds. Preliminary means that the MPC's are based on information from revieuws only. Preliminary MPC's are derived aiming at the protection of man as well as the ecosystem: MPChuman and MPCeco, respectively. Both MPC's are compared and one is selected being the preliminary MPC in air. For derivation of the MPChuman the selected compounds are divided into two groups. The first group contains 12 compounds for which limit and/or target values have already been set. For these compounds the data-set was only updated to see if these values have to be re-evaluated. It is concluded that this was not the case. The second group comprises 34 compounds, for which no limit and/or target values have been set. For these compounds information from reviews was collected. Because only reviews are consulted, uncertainty factors are applied rather rigid on results from toxicological studies. For 24 compounds a preliminary MPChuman could be derived.