Outdoor air pollution kills 3.7 million people per year around the world, according to the World Health Organization. The key to controlling the problem is knowing where it comes from. But that information is all but absent in much of the developing world. So the United Nations Environment Program is launching a low-cost tool to help officials keep watch over the air in their cities. VOA’s Steve Baragona has more from Nairobi, Kenya.

Originally published at - http://www.voanews.com/media/video/cheap-pollution-monitor-aims-to-help-world-cities/2953975.html