Air pollution continues to be a daunting challenge across the world, but a new report points to China as an important beacon of progress. According to a latest report published by Chicago University, particulate pollution in China has declined by 40% since 2013 when the Chinese government declared a "war against pollution," while it took several decades for the U.S. and Europe to achieve such reductions. The drop has also added 2 years onto the average life expectancy in China. What enabled China to make its air cleaner while also growing its economy? What still needs to be tackled?