The use of atmospheric dispersion modelling has become more common for the determination of odour impacts from existing poultry production facilities and the assessment of setback distances for new facilities. Setback distances for broiler, layer and turkey units were determined using the atmospheric dispersion model ISCST3 and the Environmental Protection Agency (EPA, Ireland) recommended criterion (C98.1-h <= 6.0 ou(E) m(-3)) and a new odour annoyance criterion (C-98,C-1-h <= 9.7 ou(E) m(-3)) developed in this study. For a typical size unit in Ireland, maximum setback distances of 660, 665 and 1035 in were calculated for 40,000 broilers, 40,000 layers and 10,000 turkeys respectively at the current limit (C-98,C-1-h <= 6.0 ou(E) m(-3)). However, if the suggested odour impact criterion (C-98,C-1-h <= 9.7 ou(E) m(-3)) is implemented, the maximum setback distances decrease to 460, 500 and 785 in for broilers, layers and turkeys, respectively. (c) 2005 Elsevier Ltd. All rights reserved.