What China can teach US about clean air

Every year, more than 4 million people around the world die prematurely from breathing dirty air. In China alone, the number of deaths attributable to air pollution exceeds 1 million a year. That figure may not come as a surprise, as we are routinely treated to images in the media of thick, sooty smog enveloping Beijing, Shanghai and other Chinese cities. But the United States' air kills, too - and it gets a lot less attention.

A 2013 Massachusetts Institute of Technology estimated that poor air quality accounts for 200,000 early deaths in the US each year, more than the number killed by car crashes and diabetes. Yet while China is aggressively tackling its air pollution problem, the US is rolling back air-quality protections in the name of economic growth - an ill-conceived strategy that will have a devastating impact on human health.

Research over the past 20 years has tied PM2.5(airborne particles with a diameter of less than 2.5 microns) to a range of adverse health outcomes, including asthma, acute bronchitis, lung cancer, heart attacks and cardio-respiratory diseases. We know, too, where most PM2.5 comes from: power plants, heavy industry and motor vehicles.