To investigate effect of short-term exposure to air-pollutants on the occurrence of stroke (Ischemic/Hemorrhagic). To determine the effect of air-pollutants on 180-day outcome after stroke.

The study design was a case-crossover study. This design is a variant of matched case control study and consists of only cases, which serve as their own controls in the analysis. The data collection was ambispective. Poor outcome was defined as modified Rankin Scale (mRS) score 3 or more. Statistical analysis was performed in STATA13.0 software. 

692 stroke (Ischemic/Hemorrhagic) patients were enrolled from Jan2012 to Oct2017. The air-pollutants studied were PM10(Particulate Matter), PM2.5, NO(Nitric-oxide), NO2(Nitric-dioxide), SO2 (Sulfur-Dioxide), CO (Carbon-Monoxide), O3 (Ozone), humidity and temperature. There was no significant association of all stroke occurrences with short-term exposure to increased air-pollutants. However, a borderline significant association was observed with simultaneous rise of NO2 and CO with OR 1.29; 95%CI 0.9to1.9. 

351 patients were recruited prospectively (235-ischemic stroke(IS), 116-hemorrhagic stroke(HS). NO2>92.16µg/m? (OR 1.96;95%CI 1.004to3.82) was found to be significantly associated with 180-day poor outcome after all stroke. Analysis on the basis of stroke subtype observed PM25>189.31µg/m?(OR2.87; 95%CI 1.005to8.19), NO2>70.93µg/m? (OR3.73; 95%CI1.24to11.18) &NOX>150.1µg/m?(OR4.4; 95%CI 1.56to12.38) to be associated with 180-day mortality after IS. A significant association with poor outcome after IS was also observed with NOx and after HS was observed with PM10 and O3 respectively.

There is no significant association of occurrence of stroke with short-term rise in air pollutants. There may be an association of stroke occurrence with simultaneous rise in NO2 and CO levels. Study also suggests effect of particulate air-pollution on mortality and 180-day poor outcome after Ischemic-Stroke and Hemorrhagic-Stroke.