A ventilation system installed in a classroom is pictured at the IGS school in Mainz, western Germany, on November 12, 2020. - At German high school IGS Mainz-Bretzenheim, a teacher's scientist husband has come up with a novel way to fight the coronavirus by designing a simple ventilation system, using pipes and a fan from a DIY store. The system, now being looked at by schools across Germany, cost just 200 euros and has proved to remove more than 90 percent of virus-carrying aerosols from the classroom. (Photo by Daniel ROLAND / AFP)