The application of techniques such as dry filtering, wet scrubbing or electrostatic precipitation to the extraction of dust from recirculated air in livestock houses has proved moderately successful. However, the volume of air which has to be handled is large and the equipment becomes impracticable for large volume houses. This review covers experimental work which has investigated the nature and composition of dust, factors affecting dust levels and ways of controlling and reducing dust by methods other than mechanical separation. The most significant factors affecting dust concentration are the type of feed and feeding system, animal activity and husbandry tasks such as bedding and weighing. Much of the work which has investigated the effect of environment on dust concentration is inconclusive. However, it was clear that increasing ventilation was not a practical method of restricting dust levels except when used as a flush technique. Several studies have shown that there were worthwhile reductions in aerial dust levels when animal fat or vegetable oil were added to the feed. It has also been shown that the dust level in a building with a slatted floor is less than that in a similar building with a solid floor. © 1997 Elsevier Science Ltd. All rights reserved.