In order to make clear the relationship the chemical substances concentration and symptom of sick house syndrome, an investigation of 62 houses in Japan has been done for 9 years. The results showed that the indoor air of many sick houses was polluted with high carbonyl compounds and Volatile Organic Compounds (VOC) concentrations exceeded the criterions of Japan Standard. In addition, high concentration was found not only in the houses which were just built or renovated, but also in the houses with well-air-tightened and low air change rate.
