Abstract A mathematical model of the formaldehyde concentrations in rooms containing particle boards with known emission-rates of formaldehyde is presented. The model is tested in three rooms in a new house. Agreement within ± 15 % is found between calculated and measured formaldehyde concentrations in the rooms before painting and without furniture, carpets, etc. It is concluded that the combined mathematical model and the analytical method may be suitable for the classification of particle boards according to their emission of formaldehyde and for predictions of formaldehyde concentrations in the indoor environment. The final recommendation, however, must await the setting of tests conditions which are discussed in the paper.