By Cat DiStasio
Air pollution is a huge problem in cities around the globe. The widespread burning of fossil fuels combined with the destruction of air-cleaning forests results in dense concentrations of smog in large urban centers. What's more, the World Health Organization estimates that air pollution contributes to 7 million premature deaths each year. To address this enormous public health problem, engineers from around the world have developed some cool (and crazy) gadgets to help clean up the air. In Italy, the world's first vertical forest have inspired designers around the world, but smaller projects are actively fighting pollution too. From a sidewalk that eats smog to an air-cleaning vacuum that turns pollution into jewelry, you'll be amazed by the ways people are working to improve air quality.