When it comes to pollution, the economic downturn could have an upside.

The Environmental Protection Agency on Tuesday reported that toxic chemical pollution from the nation's industrial plants, mines and factories declined by 6 percent in 2008, the second year in a row that companies have reported releasing less pollution.

Companies put 3.86 billion pounds of toxic chemicals into the air and water and onto land in 2008, down from 4.1 billion pounds in 2007 and 4.26 billion pounds in 2006.

Part of the explanation for the decrease is that fewer facilities reported to the EPA's annual database — known as the Toxics Release Inventory, or TRI. The decline, the EPA said, could be the result of the economic downturn.

As companies shut down or reduce manufacturing, the amount of pollution also dips.

The EPA said the economy's toll on pollution would likely be even more visible in 2009 numbers.

Air pollution decreased the most in 2008, by about 14 percent. Pollution entering lakes, rivers and streams actually increased, an uptick that the EPA said was caused in part by a large coal ash spill at a Tennessee Valley Authority power plant in Kingston, Tenn.

Other pollution indicators have also shown the link between a faltering economy and less pollution. The Energy Information Administration earlier this month predicted that emissions of the gases blamed for global warming would decline by 6.1 percent in 2009 because of a drop in energy consumption and power plants burning less coal.

The Toxics Release Inventory is released annually by the EPA and includes information on 650 chemicals from more than 21,000 facilities.