Trees can also increase the lifespan of city residents. A 30% increase in the canopy that shades the ground below trees could prevent one-third of premature heat-related deaths in European cities while reducing city summer temperatures, says a recent study of possible solutions. Researchers began by looking at premature deaths attributed to higher temperatures in 93 European cities between June and August 2015. Cities in Southern and Eastern Europe fared the worst with heat-related deaths. That mortality data was then studied along with daily average city temperatures in two scenarios. "Our results suggest large impacts on mortality due to hotter temperatures in cities, and that these impacts could be partially reduced by increasing the tree coverage to help cool urban environments," said co-author Mark Nieuwenhuijsen.