Association of proximity to polluting industries, deprivation and mortality in small areas of the Basque Country (Spain)

Background: The study is aimed at assessing social inequities in the location of polluting industries in the Basque Country, and at exploring if the effect on mortality of living near air polluting industries is modified by economic deprivation. Methods: This is a cross-sectional ecological study that uses the census sections as analysis units. Mortality from all causes, lung cancer, respiratory diseases and ischaemic heart disease were studied. Ordinal logistic regression models were fitted to assess if proximity of census sections to polluting industries is associated with deprivation. Bayesian Poisson regression models were used to explore if the association between proximity to polluting industries and mortality is modified by socio-economic deprivation. Results: Proximity to a polluting industry and deprivation are positively associated, showing a clear gradient across deprivation quintiles. In women, the risk associated with proximity to metal-processing industries grows as the deprivation of the area increases in the case of total and lung cancer mortality. In men, the interaction terms between proximity and deprivation are positive for total, ischaemic heart disease mortality, with a credibility level approaching 90%. High levels of deprivation are associated with greater risk of mortality, excepting lung cancer in women. Conclusion: There is a higher proportion of more deprived census sections around polluting industries in the Basque Country. Risks of mortality associated with proximity to polluting industries tend to be higher in more deprived areas.