Residents live in different types of tents/houses in the study area (Supplementary Materials S1 and S2). Both tents and houses have only one room without a separate kitchen, and people sleep, eat, and cook in the same room. Two types of tents and biomass stoves are used in this region . Briefly, traditional tents (23.2 m3) and advanced tents (38.5 m3) have
similar structure and air ventilation conditions, but the fabric and volume differ. Simple stoves without chimneys and chimney stoves are used for both cooking and heating in this region. Simple stoves are iron circles, each of which is supported by three iron bars (50 cm in height and 40 cm in diameter). A hole (1 0.5m2) on top of the tent ventilates smoke from simple stoves. Chimney stoves are made of thin iron sheets, and feature a combustion chamber (40 cm
in height and 40 cm in diameter), a plenum channel (15 18 60 cm3), and a chimney (2.2 m in height and 16 cm in
diameter). Yak dung is the only biomass fuel used in tents or houses in this region.