In the exhibition of the Shosoin treasures held at the Nara National Museum in 1970, air pollution in and out of the exhibit gallery as well as the show cases was studied. Sulfur and nitrogen oxides were scarcely detected in the gallery or cases. Carbon dioxide given forth by respiration of visitors was 1200 ppm in the gallery and 600 ppm in a show case. 30 minutes after the closing time the concentration of the carbon dioxide in the building fell to the background level, while in the show case its value was 500 ppm.