Concentrations and variations of fine particulate matter (PM2.5) and carbon monoxide (CO) within tents from the Nam Co and Ando regions were observed at summer 2009, in order to understand the concentrations and variations of PM2.5 and CO in these tents (or in rooms) and their main affect factors, as well as the exposure of different residents. The result indicates that the twenty-four hour average concentrations of PM2.5 and CO (V/V) in the tents without chimney are 1.272 mg x m(-3) and 5.035 x 10(-6), which are significantly higher than those of tents installed chimneys (0.097 mg x m(-3) and 0.089 x 10(-6)). Diurnal variations of PM2.5 and CO are similar and show multiple peaks, which is different with those in the eastern rural areas of China and closely connected with the behaviors of the residents within the tents. Generally, women and children spend three or four hours longer in tents than other family members every day. Children have the highest exposure of 0.972 mg x m(-3) and 0.132 x 10(-6) for PM2.5 and CO, respectively. Therefore, although the outdoor air in the Tibetan Plateau is very clean, the air of the Tibetan tents are seriously polluted and mainly caused by yak dung combustion.