Four furniture factories near İstanbul, Turkey, \vere examined for the viable microbial load of air by exposing Petri-plates containing malt-agar medium. Gencrally, the sedimentation rate, measured in number of Colony Forming Units (CFU/dm2/h), increased \vith the start of operation of the machinery. •--- In one of the factories, a modern facility equipped \vith a pneumatic particle collection and air cleaning system, the microbial load of air remained extremely Iovv (average of 4 readings was 160 CFU/dm2/h) and belo\v that measured simultaneously outdoors. Indoor levels in the other three factories were higher than those measured outdoors during operation time. The sedimentation rate was highest in one of them which was not equipped with partide collecting and aeration systems, reaching a maximum of 1587 C FU /dnr/h (average of 4 readings was -1300 CFU/dm2/h).