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 the 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. They also looked at different sizes of suspended particles, coming from the industrial pollution (PM1), the evaporations of cars, burning fuel from power plants and them fires forests and grasses (PM2.5), as well as powder 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 nitrogen dioxide concentrations were associated with 28% increased risk of stroke, 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.