Facing criticism from industry and lawmakers, the Obama administration is easing rules aimed at reducing toxic air pollution from industrial boilers and incinerators.

But administration officials maintain the health benefits of the regulation won't change.

In a proposal released Friday, the Environmental Protection Agency said it would place emissions limits on the largest and most polluting boilers. Smaller ones could meet the rule through routine tune-ups.

The Republican-controlled House passed a bill in October delaying the boiler regulation. A bipartisan bill pending in the Senate would give the EPA additional time to rewrite the rule, and for industry to comply.

Industrial boilers burn coal and other fuels to generate steam and hot water for heat and electricity. They're the second-largest source of toxic mercury emissions, after coal-fired power plants.