Only three of the 74 Chinese cities monitored by the central government managed to meet official minimum standards for air quality last year, the Ministry of Environmental Protection announced this week, underscoring the country’s severe pollution problems. The dirtiest cities were in northern China, where coal-powered industries are concentrated, including electricity generation and steel manufacturing. The ministry said in its announcement, posted on its website on Tuesday, that in the broad northern region that includes the large cities of Beijing and Tianjin as well as the province of Hebei, which surrounds Beijing, the air quality standards were met on only 37 percent of days last year. Beijing, with 20 million people, did so on only 48 percent of days, […]