The inventory names the twenty U.S. counties with the largest toxic chemical releases in 2010, the latest year for which complete data is available. Harris County topped the list in air pollution, with more than 12 million pounds of toxic emissions, about the same as in 2009. Its nearest competitor — Humphreys County, Tennessee — emitted just over 7 million pounds.
Harris also took a distant second place for surface water pollution. The county discharged more than 2.5 million pounds of wastewater. The leader was Indiana’s Spencer County with more than 24 million pounds.
The TRI shows nearly 4 billion pounds of toxic chemicals were released into the environment nationwide in 2010. Total air releases fell 6% from 2009, continuing a trend seen over the past several years. Surface water releases increased 9% and releases into land 28% since 2009, both due mainly to releases from the metal mining sector.