The strength of indoor air pollution sources is often determining the ventilation requirements in office buildings and therefore setting a limit to reductions of energy consumption in office buildings. Activities to reduce the air pollution load in buildings need to be based on knowledge about the relative importance of different sources. This knowledge should be based on sufficiently detailed identification and proper quantification of the sources in buildings.

In one office in each of three selected buildings three Field and Laboratory Emission Cells (FLECs) were mounted to the wall, floor and desk surface on representative places. During the measurements the FLECs were supplied with clean, humidified synthetic air. Air from the FLECs were sampled on tubes with Tenax TA sorbents at four different times after application (1hr, 3hrs, 6hrs and 24 hrs). Each sample was taken during a period of 50 minutes with a flow rate of 90 ml/min giving a sampling volume of 4.5 l. Similar samples were also taken from the room air and the outdoor air.

In the investigated buildings the walls are the major emitter of VOCs to the office air in the newly built or renovated office while the floor is the major air polluter in older offices. The simplified method used can give a good indication of the origin of emitted volatile organic compounds in office air. The measured changes in emission rates during the 24 hours after application of the FLEC are typically small. A great deal of these changes may be associated with uncertainties in the method. The best time for sampling chemicals seems to be after 1 hour. More research is needed on the causes of the temporal changes and the influence on emission rates and resulting room air concentrations of typical variations in temperature, humidity, ventilation rate and other environmental parameters.