"University of Virginia grad student Thomas Talhelm was living in Beijing on a Fulbright Scholarship during the winter of 2012-13, when air pollution was so bad scientists likened it to a nuclear winter. Those who could afford it were resorting to an expensive solution: air filters costing up to $1,000. Talhem built his own on the cheap, getting comparable particulate count results, and has started a company that both markets the product to middle class Chinese and shows others how to DIY."