The environmental changes in show caves have been concerned by the show cave managers and speleo-scientists. Most scientists have recognized the speleo-activities and tourist facilities as the main factors to force the environment changes in the show caves. The show caves in carbonate rocks including the water caves and dried caves are strongly influenced by the visitor flow. Great number of visitors rushing into the show caves in a short periods causes the CO2 content and temperature rapidly increase, especially in the narrow and small passages and chambers. The maximum CO2 content was 7000 ppm （May 2, 2001） in the chamber about 20 m long, 25 m wide and 58 m high in Baiyun Cave, Hebei, after about 3000 people visited for 5 hours, the temperature increased from 16 8 ℃ to 19.6℃.In some cases, the natural factors may make great changes of the cave environment . For example, the heavy rain caused the great amount of drops in Yaolin Cave,Zhejiang.CO2 concentration was obviously increased from 490800 ppm on October 30 （before raining） to 7401580 ppm on November 14, 1997 （ after raining）. The measurement results show the temperature of drop water is 0.10.6℃ higher than the cave temperature, but it is not very clear that the temperature of cave was whether increased or not in the big chambers in Yaolin Cave. In Huangxian Cave, Hubei, in the wet season, most of 1833 rim pools were over flowing, the average CO2 content in the Rim Pool Hall on October 6,2000 was 2050 ppm, in the range of 1800 ppm and 2300 ppm; the temperature varied from 17.6℃ to 19.1℃, average temperature was 18.5℃. While on August 20, 2001, when 90% of the rim pools were dried out,it was only 950 ppm of average CO2 concentration varying from 900 ppm to 1100 ppm, and the average temperature was 17.9℃, fluctuated from 15.9℃ to 21.3℃.
