Texas on top: Top 10 states by NOx emissions

Texas, which aggressively fights tighter ozone rules, produces more ozone-causing pollutants from the vents and stacks of factories, power plants and other facilities than any other state. Nitrogen oxides, known as NOx, and volatile organic compounds, or VOCs, combine to form the lung-damaging ozone when cooked in the sun.

Source: Center for Public Integrity analysis of 2011 U.S. Environmental Protection Agency figures, the most recent data. Numbers are rounded.