No associations between environmental exposures and stroke severity in a low pollution area in Sweden

Mounting evidence supports associations between air pollution and noise exposure and cardiovascular events; however, the relationships at low exposure levels and for stroke outcomes remain uncertain. The aim was to investigate the associations between environmental exposures over 1-year and 10-year periods and both stroke severity and stroke type in a registry-based cohort including people with stroke residing in a low-pollution area of Sweden. Patients with stroke admitted to the Sahlgrenska University Hospital from 2014 to 2019 were included. Stroke severity was assessed with the National Institutes of Health Stroke Scale and stroke types were ischemic and hemorrhagic. Annual residential environmental exposures (road traffic noise (L_Aeq,_24h), inhalable particulate matter (PM₁₀), and nitrogen oxides (NO_x)) were assigned from high-resolution dispersion models to participants one year and for ten years prior to stroke, respectively. Of 4066 patients, 1965 (48.3%) were women. The mean (± SD) age was 73.6 (14.0) years. A total of 1563 (28%) had moderate to severe stroke, and 3603 (88.6%) had ischemic stroke. We did not find significant associations between environmental exposures (L_Aeq,24h, NO_x, PM₁₀) and stroke severity nor stroke type. The generally low levels of exposure and low variance of these environmental factors might explain the lack of observed associations.