As our world becomes more polluted, design students entering the Electrolux Design Lab competition are sprinting toward a solution. Here's one idea called the Hand Tree, a wristband that works as a personal air purifier that cleans the air around you, and perhaps across our entire planet.Thewas created by Alexandr Kostin of the Russian Federation. It's an anti-pollution bracelet that works like a plant, taking in carbon dioxide and releasing oxygen. At the same time, it removes dust, harmful gas…