China’s major cities have some of the world’s worst smog. Record levels of air pollution crippled Beijing, the capital, for weeks last winter. The Chinese government, which had long ignored the problem, is finally taking notice. In September, China’s Cabinet announced a plan that aims to reduce the country’s heavy reliance on coal to below 65 percent of total energy usage by 2017. Last week, Beijing also announced a set of color-coded emergency measures for bad pollution days.