Double disproportionality in industrial siting in Canada.

Our study identifies industrial subsectors in Canada where a few facilities are responsible for the majority of PM2.5 and PM2.5 precursor emissions and investigates whether these facilities are disproportionately sited near structurally marginalized socio-demographic groups, indicating the existence of "double disproportionalities." We find that disproportionality in emissions exists across pollutants and subsectors. Patterns of disproportionate facility siting differ between urban and rural settings. Facility siting from "Oil and Gas Extraction" disproportionately affects more marginalized groups in urban areas, while "mining and quarrying" affects more groups in rural areas. Urban Indigenous populations are highly affected by disproportionate siting patterns for both all emitters and high emitters. Different patterns emerge when considering clusters of industrial facilities: Low-income and Black populations are more likely to reside in proximity to multiple emitting facilities. Our results support the existence of double disproportionalities for some sectors and highlight the need for research on cumulative environmental hazards.