China’s capital has become notorious for its smog but the biggest contributors to local air pollution are industrial furnaces, district heating systems, residential fires and trucks rather than power plants. Industrial firms, heating plants and residential fires in the capital and neighboring provinces consume 240 million tonnes of coal per year compared with about 130 million tonnes burned in power plants. There are many ways to assess pollution but one of the most common is to measure the amount of tiny particulates measuring 2.5 micrometers or less in diameter (PM2.5) suspended in every cubic meter of air. These tiny particles, which can be inhaled deep into the lungs, have been blamed for a variety of cancers and other respiratory diseases by the World Health Organization. […]