This makes sense. The efficiency of older stoves is just terrible. By fine-particular matter they mean smoke, or unburned wood gas. Newer EPA stoves have some steel tubes, with holes drilled in them, which introduce air into the top of the firebox. Given the stove's internal temp is high enough to cause ignition, this oxygen mixes with the unburned wood gas and ignites, providing more heat, less pollution, and greater efficiency.
One thing that also needs mentioning is that burning wood is carbon neutral, if you're harvesting wood and letting it grow back. This isn't a fossil fuel, global warming issue.