http://arstechnica.com/science/2013/07/coals-high-cost-in-china-2-5-billion-years-of-life-expectancy/
*Coal’s high cost in China: 2.5 billion years of life expectancy* Coal is the least efficient of the fossil fuels in terms of the amount of energy gained vs. CO2 released. Burning it also releases numerous toxic chemicals and particulates, which can exact a cost on a country's population in terms of reduced life expectancy and increased health costs. Figuring out the exact cost of coal use, however, is challenging because of a combination of different pollution controls and the mobility of the population. Thanks to an unusual combination of policies (some completely unrelated to pollution), China has accidentally provided the opportunity to put an exact number on the human cost of coal use. And that number turns out to be staggering: 5.5 years of reduced life expectancy that, when spread over the half-billion people of northern China, means a loss of 2.5 billion life-years.
