The EPA's annual Toxic Releases Inventory report, released Wednesday, said the drop was mostly because of decreases in hazardous air pollutant emissions, even while total air, land and water releases of toxic chemicals increased for the second year in a row.
Data for the inventory report are submitted each year to the EPA by facilities in industry sectors such as manufacturing, metal mining, electric utilities and commercial hazardous waste facilities.
The inventory "plays a critical role in EPA's efforts to hold polluters accountable and identify and acknowledge those who take steps to prevent pollution," EPA Administrator Lisa Jackson said.
"Since 1998, we have recorded a steady decline in the amount of TRI chemicals released into the air, and since 2009 alone, we have seen more than a 100-million-pound decrease in TRI air pollutants entering our communities," she said.
Among the hazardous air pollutants showing decline were hydrochloric acid and mercury, likely due to installation of control technologies at coal fired power plants and a shift to other fuel sources, the EPA said.