The association between short-term nitrogen dioxide (NO2) exposure and ischemic stroke or transient ischemic attacks (TIA): a national study in Israel

Air pollution is an environmental risk factor for stroke, but most studies have focused on fine particulate matter (PM 2.5 ), and fewer have investigated the independent association with exposure to nitrogen dioxide (NO 2 ). We conducted a nationwide case-crossover study including all ischemic stroke or transient ischemic attack (TIA) reported in the Israeli National Stroke Registry from 2014 to 2018. We obtained daily NO 2 levels from high-resolution geospatial models and linked them to residential addresses. We used distributed lag nonlinear models to assess the cumulative association of NO 2 exposure over 0–5 lag days, adjusting for PM 2.5 and temperature. We further evaluated the modification of the associations by age, sex, urbanicity, and comorbidities (ischemic heart disease, hypertension, and diabetes). We included 85,162 cases, about 54% were males, and the mean age was 71.8. Cumulative NO 2 exposure was associated with increased odds of ischemic stroke or TIA (odds ratio – OR and 95% confidence interval − 1.057 [1.034–1.081]), with the strongest effects 3–5 days before the event. The associations were more pronounced in urban areas (1.064 [1.032;1.097]) compared to suburban areas (1.045 [1.012;1.080]). Although the overall association was similar across ages and sexes, the lag-specific associations on lag days 3–5 were more pronounced in younger adults and women. Short-term exposure to NO 2 is associated with an increased risk of ischemic stroke and TIA, with differential associations across urbanicity, sex, and age groups. These results underscore the urgent need for public health initiatives to reduce NO 2 emissions.