Exposure to air pollution may be linked to an increased risk of stroke within the next five days, according to research published in the online issue of the Journal of the American Academy of Neurology, Neurology.

The meta-analysis included a review of 110 studies involving more than 18 million stroke cases.

The researchers looked at the effects of pollutants such as nitrogen dioxide, carbon monoxide and sulfur dioxide. Also, examined various sizes of suspended particleswhich come from industrial pollution (PM1), car exhaust, fuel burning from power plants and forest and grass fires (PM2.5), as well as dust from roads and construction sites (PM10).

People exposed to a higher concentration of various types of air pollution had an increased risk of stroke. Higher concentrations of nitrogen dioxide were associated with a 28% increased risk of strokey, the highest levels of ozone with a 5% increase, carbon monoxide with a 26% increase and sulfur dioxide with a 15% increase. The highest concentration of PM1 particles was associated with a 9% increased risk of stroke, PM2.5 with a 15% increased risk, and PM10 with a 14% increased risk.

“There is a strong and significant association between air pollution and the occurrence of stroke, as well as death from stroke within five days of exposure,” explains study author Ahmad Tubassi from the University of Jordan in Amman. “This highlights the importance of global efforts to create policies that reduce air pollution. Doing so can reduce the number of strokes and their consequences,” he adds.