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The goal of the present study is to improve indoor air quality in a film storage and surrounding environment in the National Research Institute for Cultural Properties, Tokyo. This report addresses the estimation of emission sources of acetic acid in the film storage and adjacent preparation room,and presents an experiment to remove acetic acid from paper photographic enclosures kept as archives. To estimate emission sources of acetic acid, concentration and ventilation amount of acetic acid were measured in the film storage and the preparation room. It was found that air containing acetic acid flowed to the preparation room from the film storage and that a large volume of acetic acid had been emitted from cabinet 3 in the preparation room. There were aged films in the film storage and paper photographic enclosures which had absorbed acetic acid in this cabinet. Consequently, it was considered that acetic acid concentration of the preparation room was high. Removing the paper photographic enclosures from the preparation room would be the best way to reduce acetic acid. However, they should be kept as archives since they contain much information about the films. Therefore, seasoning of the enclosures wasattempted. As a result, their acetic acid emission rate was decreased in the first 35 days of seasoning. Furthermore, A-D strips were used to check the removal of acetic acid from the enclosures. The color of the A-D strips was changed in accordance with acetic acid concentration of the samples. This result was consistent with the trend of emission rate decay shown by emission test. Thus A-D strips were beneficial in checking easily the removal of acetic acid from the paper photographic enclosures.

Acetic acid concentration in the exhibition cases of a certain museum did not fall for 15 years after its opening. There was no detailed information on the interior finishing material used at the time of its construction nor on the structure of the cases. There was only one door in each exhibition case and ventilation was difficult. When this door was repaired, a part of the wall was removed and pieces of the wall were used to plan a remediation measure. It was found that the wall was composed of 5 layers:steel,plywood, paper material, plywood with holes, and surface finishing cloth. Test pieces of each composing material of the wall were set in a material test chamber and clean air was pumped through it to collect emission gas in a TENAXTMtube.Gas-chromatograph/mass spectrometer was used for identification of the emission gases. About 30 kinds of chemicals were identified from the surface finishing cloth. On the other hand, 52 kinds of chemicals were identified from the paper material. It was found that a large amount of acetic acid was stored in the paper material and emitted to the space in the exhibition case. After bake-out treatment,quantity of acetic acid decreased to 39% from the original. The same result was obtained when acetic acid removal absorbent of special activated carbon was placed on the test pieces. The latter method was thus applied to actual exhibition cases of similar size. For evaluation of the effectiveness of the treatment, air from the two cases was sampled into TENAXTM tubes: one case was treated with absorbent 36 days before sampling and the other was treated 2 days before sampling. As for the case which wastreated 2 days before, the detected number of chemicals was less than that in the other case. Quantity of acetic acid decreased heavily in the case which was treated 2 days before, but a large amount of acetic acid was detected in the other case. It is suggested that there was a reservoir layer of acetic acid far from the surface. As a result, the source of theacetic acid could be specified. In conclusion,it was found that it is necessary to treat these exhibition cases repeatedly with acetic acid absorbent. It is thought that the fundamental solution for these cases is to peel off the cloth,install a covering material on the plywood and finally apply surface finishing cloth in order to avoid emission from the paper material.

One problem in the museum environment is air pollutants in airtight display cases, some of which cause adverse effects on artifacts inside.Their gases,especially acetic acid gas, are mainly emitted from interior materials used in display cases. There are two systems for reducing the level of pollutants inside the enclosure.One is an active adsorption filter fan system and the other is a ventilation fan system that takes the clean air from the exhibition room.The present paper reports on the test using these systems to control acetic acid gas pollutants in a display case. Several measurements were conducted to see air distribution, air exchange rate and acetic acid gas concentration in a display case. The display case used in the experiments was made for environment test. Performance of active adsorption air filter within enclosures and ventilation effect by the fan were also measured. As a result it was found that acetic acid gas concentration in the display case decreased to 30% by using an adsorption filter fan system and it became of equal level to that in an exhibition room by using a ventilation system. Effects of control of pollutantsby each system were evaluated by using ventilation volume with clean air (i.e. equivalent ventilation volume). Changes of gas concentration in the display case were estimated through prediction formula using factors of equivalent ventilation amount and operating period of the fan. From the results it was estimated that good air environment in the display case was maintained by operating an adsorption filter fan system for about two hours a day.

Recently, display cases in museums have improved in airtightness.On the other hand, there is a risk that artifacts in display cases may be exposed to chemical gases if there is gas emission from the interior materials used in the display cases. Also it is thought that gas concentration increases with time. However, change in gas concentration in display cases has not been made clear until now.To confirm such a change,it is necessary to repeat gas sampling in a specific time cycle and to keep the display cases closed during test period. But if the cases are kept closed, confirming change in gas concentration is difficult since measuring devices cannot be easily set or removed.In order to solve this problem,a display case was made for environmental testing and gas concentration was measured. This paper reports the change in acetic acid gas concentration in the display case as confirmed by measurement. It also compares the acetic acid emission rate of the interior materials obtained from the measurement of the display case and that obtained from chamber test. As a result, it was found that there was little difference in emission throughout the experiment. Gas concentration obtained by the measurement was corrected by removing the effect of gas sampling. This corrected gas concentration was consistent with that obtained through prediction formula based on initial gas concentration. In addition, emission rate of the interior materials obtained by chamber test and by the present measurement was similar. From these results, it was found that it is possible to predict change in gas concentration in display cases by obtaining initial gas concentration and that chamber test is an effective method to estimate gas concentration in display cases.