The art of the possible: experience and practice in health impact assessment in New South Wales.

Richard Seymour was appointed the first Inspector of Nuisances in Sydney in 1884. His work approving and inspecting opium dens, privies, abattoirs and tanneries contained many of the elements we now call health impact assessment (HIA). Indeed the entire corpus of planning and environmental protection legislation and the building codes have encoded provisions which are a distillation of the accumulated wisdom and prejudice formed in doing these assessments. In this article I have attempted to distil some of the lessons learned in the commissioning and conduct of environmental health impact assessments in NSW since 1990, in the hope that some of these at least will be of direct relevance to the conduct of HIA in other settings.