In 2010, researchers at the Political Economy Research Institute of the University of Massachusetts Amherst ranked DuPont as the fourth-largest corporate source of air pollution in the United States. DuPont released a statement that 2012 total releases and transfers were 13% lower than 2011 levels, and 70% lower than 1987 levels. Data from the EPA's Toxic Release Inventory database included in the Political Economy Research Institute studies likewise show a reduction in DuPont's emissions from 12.4 million pounds of air releases and 22.4 million pounds of toxic incinerator transfers in 2006 to 10.94 million pounds and 22.0 million pounds, respectively, in 2010. Over the same period, the Political Economy Research Institutes Toxic score for DuPont increased from 122,426 to 7,086,303.