Nighttime lighting and dirty air have been linked to an increased risk of stroke

Chinese scientists conducted a prospective cohort study and concluded that levels of outdoor lighting at night and air pollution are independently associated with an increased risk of cerebrovascular disease. The publication of this study appears in the journal Stroke. Kun Chen from Zhejiang University and colleagues from different research centers in China analyzed data from 28302 Ningbo residents included in the Yinzhou District Cohort in 2015-2018 (total follow-up duration was nearly 128 thousand person-years). Nighttime street lighting and air pollution levels were determined by satellite imagery and land use regression models. Stroke diagnoses were recorded from medical registers and death certificates. Cox proportional hazards models were used to process the data.

A total of 1287 strokes (777 ischemic and 133 hemorrhagic) occurred in participants during follow-up. Both nighttime lighting and air pollution were found to be associated with an increased risk of cerebrovascular disease in general. The hazard ratio (HR) per quartile increase in the index was 1.17 (95 percent confidence interval 1.06-1.29) for outdoor lighting at night; 1.25 (95 percent confidence interval 1.12-1.39) for suspended particulate matter ≤ 2.5 micrometers in diameter; 1.14 (95 percent confidence interval 1.06-1.22) for particulate matter ≤ 10 micrometers in diameter; and 1.21 (95 percent confidence interval 1.06-1.38) for nitrogen oxide (NO2). These HRs were similar for ischemic strokes, but a similar pattern was not seen for hemorrhagic strokes. No interaction of nighttime light and air pollution in influencing risk was observed.