I wonder how many of those stoves are older models that don't have a pipe air source to draw intake air from outside, or are newer, but are unconnected.  It would be curious to see how just having a stove with a proper intake tube connected might change the health of the occupants.  Does a proper connected intake tube reduce respiratory problems from a wood stove?

If any researchers from UAF or UAA are listening, it would make for an interesting study.  Have say, three villages right next to each other (or near) that have a history of respiratory issues (and use wood heat), and then set one as a control using their existing wood stoves (but being studied), one that uses newer efficient stoves that do not have a intake tube connected, and the third village has same, newer efficient stoves with intake tube connected.  Then after studying the effects, have funding already set aside to bump all up to the new stoves (with or with/out intake connected) at the end of the study.