It is a common phenomenon that fresco surfaces are covered with soot in temples of Tibet. In this study, soot from a fresco surface of Samye Monastery in Tibet was studied by scanning electron microscopy (SEM), infrared spectrometry (IR) and cross-sectional analyses. The results show that the thickness of soot particles is about 80 μm, and that it consisted of saturated fatty glycerides or saturated fatty acids with amounts of carbon particles. The environmental testing results show that the burning of butter lamps causes volatile organic gases and particulate matters that badly exceed permitted levels.