- BACKGROUND: Differential exposure to environmental hazards is one component of the social gradient in health. Few studies have investigated the association between socioeconomic characteristics and environmental hazards in a Canadian context. We assessed the relationships between pollution emissions and socio-economic characteristics for 27 municipalities on Montreal Island. METHODS: Pollution emissions were determined using Environment Canada's National Pollutant Release Inventory (NPRI) for the periods 1995-1996 and 2000-2001. Variables included the number of reporting industries, the average annual releases, and the average annual releases density. These data were cross-referenced with socio-economic data from the 1996 and 2001 Canadian Censuses, respectively. RESULTS: For both periods, pollution measures were inversely related to the average monthly amount of owners' major payments, the average income of households, the proportion of workers in the tertiary sector, and the proportion of individuals with a university education. Pollution measures were positively associated with the unemployment rate, the proportion of workers in the secondary sector, and the proportion of individuals with less than high school education. CONCLUSION: Socio-economic characteristics are associated with municipal-level pollution emissions on Montreal Island. Whether higher emissions are indicative of higher pollution exposure requires further investigation.