The risk of suffering an ischaemic stroke, the most common type of cerebrovascular event, is 16 percent less in people who have green spaces less than 300 meters from their homes. The study took into account information on exposure to three atmospheric pollutants linked to vehicle traffic in more than three and a half million people selected from among the 7.5 million residents of Catalonia, over the age of eighteen who had not suffered a stroke prior to the start of the study.