Air pollution and daily admissions for chronic obstructive pulmonary disease in 6 European cities: results from the APHEA project

TLDR

Evidence suggests a causal link between air pollution and COPD admissions, though mechanisms and interactions remain unclear. The study examined short‑term effects of air pollution on COPD hospital admissions across Europe. Using APHEA data from six European cities, the authors applied Poisson regression controlling for seasonality, influenza, weather, and autocorrelation, then pooled city‑specific coefficients weighted by inverse variance to estimate overall pollutant effects. A 50 µg/m³ increase in daily pollutant levels was associated with modest increases in COPD admissions (SO₂ RR 1.02, black smoke RR 1.04, PM 1.02, NO₂ 1.02, ozone 1.04), confirming a consistent but weaker association than in North America.

Abstract

We investigated the short-term effects of air pollution on hospital admissions for chronic obstructive pulmonary disease (COPD) in Europe. As part of a European project (Air Pollution and Health, a European Approach (APHEA)), we analysed data from the cities of Amsterdam, Barcelona, London, Milan, Paris and Rotterdam, using a standardized approach to data eligibility and statistical analysis. Relative risks for daily COPD admissions were obtained using Poisson regression, controlling for: seasonal and other cycles; influenza epidemics; day of the week; temperature; humidity and autocorrelation. Summary effects for each pollutant were estimated as the mean of each city's regression coefficients weighted by the inverse of the variance, allowing for additional between-cities variance, as necessary. For all ages, the relative risks (95% confidence limits (95% CL)) for a 50 microg x m(-3) increase in daily mean level of pollutant (lagged 1-3 days) were (95% CL): sulphur dioxide 1.02 (0.98, 1.06); black smoke 1.04 (1.01, 1.06); total suspended particulates 1.02 (1.00, 1.05), nitrogen dioxide 1.02 (1.00, 1.05) and ozone (8 h) 1.04 (1.02, 1.07). The results confirm that air pollution is associated with daily admissions for chronic obstructive pulmonary disease in European cities with widely varying climates. The results for particles and ozone are broadly consistent with those from North America, though the coefficients for particles are substantially smaller. Overall, the evidence points to a causal relationship but the mechanisms of action, exposure response relationships and pollutant interactions remain unclear.