It is probably because a billion? people still use open wood fires indoors with poor ventilation. Visualize a fire in the middle of a hut with a pot on it and a

It is probably because a billion? people still use open wood fires indoors with poor ventilation. Visualize a fire in the middle of a hut with a pot on it and a small hole in the ceiling. AQI in that hut is going to be very bad. Creating systems where people can afford to use propane or other gas stoves are a huge win for the health of humanity and ecosystems.