Apparently they're not as great as people have been thinking

https://www.theguardian.com/environment/2020/dec/18/wood-bur...

Or wood burning fireplace inserts that draw combustion air from outside and expel the fumes/combustion byproducts outside as well. Not ideal for local air quality, but essentially eliminates indoor pollution from them.

Well sure, if you are the only person for miles that uses a fireplace.

Additionally, I think people who are outdoors still have to breathe air.

To that point -- last summer, my friends moved from a mountain town under constant threat of wildfire to a pleasant spot by a lake in the Midwest -- their new neighbor keeps a fire burning 24/7, so they still get to enjoy the terrible air quality all winter long.

Unless it does turn wood into a pure gas without a trace of sulfur, silica etc. it must emit such stuff. Or it comes with filters cleaning fine particles, nitric oxide etc. In the end it does emit CO2.

Wood pellets largely solve this.