Long-term exposure to low-level ambient air pollution and incidence of stroke and coronary heart disease: a pooled analysis of six European cohorts within the ELAPSE project

Abstract

Background Long-term exposure to outdoor air pollution increases the risk of cardiovascular disease, but evidence is unclear on the health effects of exposure to pollutant concentrations lower than current EU and US standards and WHO guideline limits. Within the multicentre study Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE), we investigated the associations of long-term exposures to fine particulate matter (PM 2•5 ), nitrogen dioxide (NO 2 ), black carbon, and warm-season ozone (O 3 ) with the incidence of stroke and acute coronary heart disease.Methods We did a pooled analysis of individual data from six population-based cohort studies within ELAPSE, from Sweden, Denmark, the Netherlands, and Germany (recruited 1992-2004), and harmonised individual and area-level variables between cohorts. Participants (all adults) were followed up until migration from the study area, death, or incident stroke or coronary heart disease, or end of follow-up (2011-15). Mean 2010 air pollution concentrations from centrally developed European-wide land use regression models were assigned to participants' baseline residential addresses. We used Cox proportional hazards models with increasing levels of covariate adjustment to investigate the association of air pollution exposure with incidence of stroke and coronary heart disease. We assessed the shape of the concentration-response function and did subset analyses of participants living at pollutant concentrations lower than predefined values. FindingsFrom the pooled ELAPSE cohorts, data on 137 148 participants were analysed in our fully adjusted model. During a median follow-up of 17•2 years (IQR 13•8-19•5), we observed 6950 incident events of stroke and 10 071 incident events of coronary heart disease. Incidence of stroke was associated with PM 2•5 (hazard ratio 1•10 [95% CI 1•01-1•21] per 5 μg/m³ increase), NO 2 (1•08 [1•04-1•12] per 10 µg/m³ increase), and black carbon (1•06 [1•02-1•10] per 0•5 10 -⁵/m increase), whereas coronary heart disease incidence was only associated with NO 2 (1•04 [1•01-1•07]). Warm-season O 3 was not associated with an increase in either outcome. Concentration-response curves indicated no evidence of a threshold below which air pollutant concentrations are not harmful for cardiovascular health. Effect estimates for PM 2•5 and NO 2 remained elevated even when restricting analyses to participants exposed to pollutant concentrations lower than the EU limit values of 25 µg/m³ for PM 2•5 and 40 µg/m³ for NO 2 .Interpretation Long-term air pollution exposure was associated with incidence of stroke and coronary heart disease, even at pollutant concentrations lower than current limit values.

Using Distributed Lag Non-Linear Models to Estimate Exposure Lag-Response Associations between Long-Term Air Pollution Exposure and Incidence of Cardiovascular Disease

“…In two recent systematic reviews with meta-analyses, increased risks for MI by 6% (95% CI −2–8%) [ 3 ] and 4% (95% CI 1–9%) [ 8 ] per 5 μg/m 3 in relation to long-term PM 2.5 exposure were reported. However, in a recent pooled analysis of six European cohorts within ELAPSE, no association was shown between baseline PM 2.5 and CHD [ 11 ].…”

“…Heterogeneity could also be due to differences in exposure assessment where studies either used monitoring stations data, land-use regression, spatiotemporal models, satellite data, or dispersion modeling with varying degrees of resolution (from 20 m × 20 m to 48 km × 48 km). In relation to baseline exposure, a 10% risk increase for stroke per 5 μg/m 3 PM 2.5 was reported in the ELAPSE study [ 11 ]. This study results suggest that recent 5-years exposure may be of greater importance compared with 5–10-years prior to the event, but the precision in the estimates was low.…”

“…Among six European cohorts, pooled analyses within ELAPSE showed a 10% risk increase for stroke and a 2% increase for CHD per 5 μg/m 3 PM 2.5 at baseline. However, the latter was not statistically significant [ 11 ]. In addition, in a recent study from Canada, 10-year mean exposure to PM 2.5 showed a 12% increased risk per 5 μg/m 3 for incident stroke [ 12 ].…”

Ambient Particulate Air Pollution and Daily Hospital Admissions in 31 Cities in Poland

“…Associations between ambient air pollution and adverse health effects are well documented, with both long-term [1-3] and short-term health impacts [4][5][6]. Studies concerning exposure influence focus on outdoor air pollutants such as particulate matter (PM) [1][2][3][4][5][6], ozone (O 3 ) [7][8][9] and nitrogen dioxide (NO 2 ) [10,11]. The health effects of air pollution include cardiovascular diseases and symptoms [6,9,12,13], and respiratory problems [9,13,14], as well as premature mortality [1][2][3]5,7,[9][10][11][12].…”

“…Studies concerning exposure influence focus on outdoor air pollutants such as particulate matter (PM) [1][2][3][4][5][6], ozone (O 3 ) [7][8][9] and nitrogen dioxide (NO 2 ) [10,11]. The health effects of air pollution include cardiovascular diseases and symptoms [6,9,12,13], and respiratory problems [9,13,14], as well as premature mortality [1][2][3]5,7,[9][10][11][12]. Each of these health effects can be represented by a need for hospitalization, and many studies have examined the relationship between short-term changes in air pollution and the hospital admission rates in the exposed population [4,6,12,15].…”