Fine particles (4 -700 nm), odour and VOC emissions before and after the used supply airfilters were studied in a ventilation unit. The pre-filter (G3) did not collect fine particles at thetest conditions, but acted as a source of particles 50-300 nm in size. The F7 fine filter, locatedafter the pre-filter, collected quite effectively even the finest particles. Sensory evaluationshowed that intensity of odour was highest after the F7 fine filter. VOC analyses did notclearly reveal which compounds caused the odour released from the filters.The study showed that the presence of fine particles did not contribute significantly to theodour perception in the supply air. Congruent to the previous findings, odour emission seemsto be related to compounds that originate from coarse particles.