Long-Term Exposure to Outdoor Ultrafine Particles and Black Carbon and Effects on Mortality in Montreal and Toronto, Canada

This report presents a study that assessed associations between long-term exposure to outdoor ultrafine particles (UFPs) and black carbon with mortality using several modeling approaches. The investigators applied exposure models developed through mobile monitoring in Toronto and Montreal to 1.5 million Canadian adults residing in both cities.

The exposure models that combined land use regression and machine learning models performed slightly better versus models that used land use regression alone. Long-term exposures to UFP number concentrations and black carbon were positively associated with mortality in single-pollutant models, but effect estimates were sensitive to adjustment for co-pollutants and UFP size.