Kitora Tumulus, located in the southern part of the old capital, Heijo-kyo, in Nara prefecture, was built around the 8th century. The interior of the stone chamber was coated with plaster, like at Takamatsuzuka Tumulus. Mural paintings depicting old Chinese gods were first discovered by fiberscope in 1983. The excavation work by Bunkacho (Agency for Cultural Affairs) was started on 28th January, 2004. In this report, measurements of the atmospheric composition and air pollutants in the stone chamber conducted before excavation is described. All the sample air was collected on site and was taken to the laboratory for chemical analysis, which was entrusted to Shimadzu Corporation. Air in the stone chamber was collected through a pipe inserted into a hole that was made by a thief in old times. To analyze the atmospheric composition of nitrogen, oxygen and carbon dioxide, air was sampled in a polyethylene bag and was analyzed by gas chromatograph GC-14BT, Shimadzu Corporation. Acidic or alkalic pollutants were collected by bubbling through a sampling solution like boric acid or sodium hydroxide solution and were analyzed by ion chromatography and liquid chromatography. Organic contaminants were trapped by TENAX tube and analyzed by gas chromatograph/mass spectrometer GCMS-QP 2010, Shimadzu Corporation. Air floating fungi were driven into culture plates through a pin hole sampler and were cultured in an incubator. Colony forming units were counted after incubation. Results were as follows: oxygen 21.80%, nitrogen 77.40%, carbon dioxide 1,088 ppm, methane 1.7 ppm, water content 0.70%, ammonia gas <0.3 ppm, formic acid <1.2 ppm and acetic acid <1.2 ppm. Many volatile organic compounds found also in outdoor air were detected at equivalent concentration. Poisonous gases were not detected. It was found that atmospheric composition and air pollutants were same as in outdoor air. Leakage of outdoor air into the stone chamber was suspected to have been caused by insufficient covering of soil after theinvestigation conducted in 1983
