This is a paper from the Proceedings of the U.S. EPA and Air & Waste Management Association Conference: Emission Inventory: Living in a Global Environment
The paper was co-authored by James E. Houck and Paul E. Tiegs of OMNI Environmental Services; Robert C. McCrillis of the U.S. Environmental Protection Agency; and Carter Keithley and John Crouch of the Hearth Products Association
It provides some useful context on how optional heating fuels compare when all their impacts are considered.