Nickel ore is smelted on site at Norilsk. The smelting is directly responsible for severe pollution, generally acid rain and smog. By some estimates, 1 percent of global emissions of sulfur dioxide comes from there. Heavy metal pollution near Norilsk is so severe that mining the surface soil is now economically feasible due to the soil acquiring such high concentrations of platinum and palladium.The Blacksmith Institute included Norilsk in its 2007 list of the ten most polluted places on Earth. The list cites air pollution by particulates (including radioisotopes strontium-90, and caesium-137 and metals nickel, copper, cobalt, lead and selenium) and by gases (such as nitrogen and carbon oxides, sulfur dioxide, phenols and hydrogen sulfide). The Institute estimates four million tons of cadmium, copper, lead, nickel, arsenic, selenium and zinc are released into the air every year. The Russian Federal State Statistics Service named Norilsk the most polluted city in Russia. In 2010, Norilsk produced 1.924 million tons of carbon pollutants, nearly six times more than the 333 thousand tons generated by Russia's second most polluted city, Cherepovets. According to an April 2007 BBC News report, Norilsk Nickel accepted responsibility for what had happened to the forests, and insisted they were taking action to cut the pollution. For the period up to 2015–2020 the company expects to reduce sulfur dioxide emissions by approximately two-thirds, but claims it is hard to guarantee this pace of reduction because they are still developing the technology.