The U.S. Environmental Protection Agency (EPA) has proposed changes in emission standards for incinerators and boilers that burn solid waste.

The proposed changes to the Clean Air Act would affect the highest emitting boilers in the United States, including boilers located at refineries, chemical plants and other industrial facilities. The EPA said in a news release it is proposing more targeted revised emission limits “that provide industry practical, protective, cost-effective options to meet the standards.” The agency said the boilers affected comprise 0.4 percent of all boilers in the nation.

The EPA said the standards will reduce emissions of harmful pollutants including mercury, lead, cadmium, nitrogen dioxide and particle pollution.

The EPA also is proposing changes in how to determine which non-hazardous secondary materials would be considered solid waste and which would be considered fuel. This distinction would determine whether a material may be burned in a boiler or whether it must be burned in an incinerator.