Air quality, stroke, and coronary events: results of the Heinz Nixdorf Recall Study from the Ruhr Region.

Background: Studies have shown that air pollution is associated with cardiopulmonary mortality, but there has been less research of the possible effect of air pollution on stroke and non-fatal coronary events. The Heinz Nixdorf Recall (HNR) study addressed the question of the effect of long-term air pollution on stroke and coronary events. Ambient acoustic noise was also considered as a risk factor.

Methods: The HNR study, initiated in 2000, is a prospective, population-based cohort study in the Ruhr region of Germany. Long-term exposure to fine-particle dust (PM10, PM2.5 and PM(2.5abs) [carbon black content]) and traffic noise at the subjects' home addresses were determined using land-use regression and dispersion models, respectively. Strokes and coronary events were ascertained from patient records by an independent end-point committee on the basis of predefined study criteria. The adjusted hazard ratio (HR) was calculated using Cox regression analysis for an increase in concentration from the 5th to the 95th percentile for each exposure.

Results: Data from 4433 subjects were evaluated. The incidence of stroke was 2.03 per 1000 person-years (PY), and that of coronary events was 3.87 per 1000 PY. The highest hazard ratios for stroke were seen for PM10 (HR 2.61, 95% confidence interval [CI] 1.13-6.00) and PM2.5 (HR 3.20, 95% CI 1.26-8.09). The highest hazard ratios for coronary events were found for PM10 (HR 1.07, 95% CI 0.56-2.04) and for PM(2.5abs) (HR 1.37, 95% CI 0.80-2.36).

Conclusion: Long-term exposure to fine-particle dust is associated with a higher risk of stroke, regardless of the subject's exposure to noise at his or her home address. The results for coronary events are less clear, but still suggest increased risk.