Ventilation systems for buildings in urban areas.

The properties of particulate filters and gas adsorption filters have been studied to determine the opportunities available for effectively cleaning the outdoor air supplied to buildings located in urban environments. Class F85 fine filters were studied to determine their collecting efficiency for both atmospheric dust and particulate P AH. Activated carbon adsorption filters were tested to establish their collecting efficiency for toluene, m-xylene and benzene in the concentration range of 1-10 ppm. Long-term tests were also run on a carbon filter in a building in central Stockholm. Moreover, the indoor pollutant concentrations that can be expected following briefly increased outdoor contents were calculated. The results show that a reduction in the outdoor air flow under such circumstances may be advisable as a supplement to cleaning of the outdoor air.