Cooling equipments have been remarkably introduced to school classrooms recently, and the saturation level of air conditioners in public schools is reached almost 100% in Tokyo City Area. Before cooling equipments were installed to classrooms, an appropriate amount of ventilation might have been maintained because windows of classrooms were mostly open during summer period. On the other hand, the ventilation rates were often reduced during winter period because of less frequency of window opening. Such less ventilation and worse air quality could be caused during summer period as well in accordance with the introduction of cooling equipments. Indoor air environment audit in schools has been conducted regularly by local government in Japan. The audit is conducted every two months in large scale schools which total floor area was over 8000 m2, and conducted generally once or twice a year in all schools irrespective of school size. Although the results of this audit could be useful to realize the indoor air quality in schools during various seasons, the results of the measurements are little made public from the local government. Therefore the results of the audit were used as the evidence in previous study. In the Law for Maintenance of Sanitary Environment in Buildings, it is demanded the CO2 concentration in the room to be 1000 ppm or less. In the previous study, it was reported that the mean CO2 concentration in the target elementary school classrooms was blow 1000 ppm during summer and midterm period. Furthermore the mean CO2 concentration in the secondary school classrooms was above 1000 ppm during all periods in the previous study. Recently indoor air quality monitoring in public building has been conducted worldwide. The French Indoor Air Quality Observatory (OQAI) was commissioned to assess children's exposure to various indoor air pollutants in schools. In the French study, the ICONE (Indice de CONfinement d'air dans les Ecoles) index was used to evaluate air stuffiness during occupied periods. One of the purposes of this study is to use the ICONE index to the results of air environmental audit for school classrooms in Tokyo district X. The analyzed schools in this study are elementary and secondary public schools located in Tokyo metropolitan district X. The period of analysis was set as 6 years from 2007 to 2012 fiscal year. The following conclusions were obtained;
1) In 63 % of elementary schools and 20 % of secondary schools, the ICONE index during summer period showed the lowest value, i.e., the lowest air stuffiness, and that during winter period showed the highest.
2) During summer period the percentage of schools with a ICONE score of 3, 4 or 5 in secondary schools was significantly larger than that in elementary schools. During winter period the difference in the above percentage between elementary and secondary schools was contrastively small.
3) The tendency that the windows are apt to close by introducing cooling equipments might be more detected in secondary schools than elementary schools.
4) The relationship between the number of occupants and the suspended particles concentration was not clear. The evidence that students or their activity are primary source of particulate matter was not obtained.
5) The worldwide data comparison for IAQ in schools could be useful, and the results of the audit should be utilized as feedback information to improve the indoor air quality.
