Indoor air pollution in museum display cases

Formic acid and acetic acid are indoor air pollutants that will engage in corrosion or othermaterial deterioration processes. Objects attacked by these compounds can be destroyedbeyond rescue by any conservation treatment. This is a special concern in the museumenvironment, as these acids are emitted from a range of display construction materials,including wood products. It is demonstrated that high concentrations of those acids can beobtained in confined spaces, such as cases, which often are characterized by a low airexchange rate and a high inner surface to volume ratio. By passive sampling, concentrationsof 477 g/m3 formic acid and 11 327 g/m3 acetic acid were measured in a case with oakwood shelves. A lead coupon in the case was heavily corroded after 14 months. Wheneverpossible, non-emissive construction materials should be used for display areas for museumobjects.