A small boy walks through the smog of Donglu, on the outskirts of Linfen, where villagers have difficulty in selling their crops because of the severe pollution. Linfen, a city of about 4.3 million, is one of the most polluted cities in the world. China’s increasingly polluted environment is largely a result of the country’s rapid development and consequently a large increase in primary energy consumption, which is almost entirely produced by burning coal.