The general realisation that odour policy must be based on sound, scientific odour measurement techniques has resulted in recent major developments in olfactometry and its acceptance as a legitimate environmental assessment procedure. This article reviews progress in this field, in North America and Australasia, where policy tended to be based on the simple avoidance of nuisance around plants, and in Northern Europe, where the quantitative approach to odour policy has been more successful, with workable Europe-wide standards being developed. Extensive research and development, supported by interlaboratory testing programs, clearly demonstrated problems with repeatibility and reproducibility of testing results prior to 1995. This work identified the need for standardised olfactometry practices and better management of odour panel members. The widespread acceptance of forced choice dynamic olfactometry as the preferred measurement method is encouraging, although a practical internationally accepted standard for olfactometry will not be attained until testing results are ‘anchored’ to a standard reference material.