A “war against pollution” declared by China’s leaders is getting a boost from the slowing economy as the government forces bloated industries like steel, cement and glassmaking to slim down. The results of cuts in overcapacity are already visible in notoriously smoggy Beijing. Official air-pollution data released by China’s government and monitoring by the U.S. embassy show levels of fine-particulate matter damaging to human health—known as PM2.5—fell more than 15% in the capital in the first half of 2015, compared with a year earlier. The city’s 21 million residents have been greeted with unusual stretches of blue skies. While measures taken by Beijing are partly behind the change, just as important is what’s happening in the sprawling industrial areas that encircle it. The bleak industrial city of Shahe, 200 miles south of the capital, boomed for much of this century. These days, small glass producers there that haven’t […]