Natural-cause mortality and long-term exposure to particle components: An Analysis of 19 European cohorts within the multi-center ESCAPE project

Abstract

Background: Studies have shown associations between mortality and long-term exposure to particulate matter air pollution. Few cohort studies have estimated the effects of the elemental composition of particulate matter on mortality. oBjectives: Our aim was to study the association between natural-cause mortality and long-term exposure to elemental components of particulate matter. Methods: Mortality and confounder data from 19 European cohort studies were used. Residential exposure to eight a priori–selected components of particulate matter (PM) was characterized following a strictly standardized protocol. Annual average concentrations of copper, iron, potassium, nickel, sulfur, silicon, vanadium, and zinc within PM size fractions ≤ 2.5 μm (PM<inf>2.5</inf>) and ≤ 10 μm (PM<inf>10</inf>) were estimated using land-use regression models. Cohort-specific statistical analyses of the associations between mortality and air pollution were conducted using Cox proportional hazards models using a common protocol followed by meta-analysis. results: The total study population consisted of 291,816 participants, of whom 25,466 died from a natural cause during follow-up (average time of follow-up, 14.3 years). Hazard ratios were positive for almost all elements and statistically significant for PM<inf>2.5</inf> sulfur (1.14; 95% CI: 1.06, 1.23 per 200 ng/m³). In a two-pollutant model, the association with PM<inf>2.5</inf> sulfur was robust to adjustment for PM<inf>2.5</inf> mass, whereas the association with PM<inf>2.5</inf> mass was reduced. conclusions: Long-term exposure to PM<inf>2.5</inf> sulfur was associated with natural-cause mortality. This association was robust to adjustment for other pollutants and PM<inf>2.5</inf>.