On Dec. 23, the U.S. Environmental Protection Agency published proposed rules that would amend its March 2011 final rulesestablishing air toxics standards for industrial, commercial and institutional boilers.  The EPA is proposing a wide range of changes, including different emission standards, revised work practice standards, and changes to the boiler subcategories. Comments are due on both rules by Feb. 21, 2012. Comments should be submitted electronically at www.regulations.gov.