Association between short-term exposure to ultrafine particles and hospital admissions for stroke in Copenhagen, Denmark

Abstract

The relevance of ultrafine particles (UFPs, particles 10), nitrogen oxides (NO_x) and carbon monoxide (CO) (measured at single background station) and hospital admissions for stroke in Copenhagen (2003−2006). Of 7485 stroke admissions, 6798 were ischaemic and 687 haemorrhagic, 3485 mild, and 2248 severe. Of the ischaemic stroke cases, 1204 had AF and 5273 did not. We found significant positive association with exposure to UFPs, NO_x and CO, and ischaemic strokes, and UFPs and NO_x and mild strokes, 4 days before admission. The strongest associations were with UFPs. Exposure to UFPs lead to a 21% increase in hospital admissions (per interquartile range of 5-day averages; 95% confidence interval 4–41%) for mild ischaemic stroke of without AF (likely thrombotic origin). Our results indicate possible effects of traffic-related air pollution, mainly UFPs, on hospital admissions for ischaemic stroke, especially for mild ischaemic stroke of likely thrombotic origin (without AF). These are novel findings regarding the relevance of UFPs and the heterogeneous effect of air pollution on the severity and origin of stroke, and need confirmation by other data.