Control Strategies for Gaseous Contamination in Museums: a New Method for Assessing Environmental Risk

In 1995-1996 a “Museum Campaign” using environmental reactivity coupons (ERCs) was begun to assess the air quality in and around a large number of cultural heritage sites throughout Italy. Analysis of the resulting reactivity monitoring database showed that the outdoor air quality does not (generally) meet the specified acceptance criteria for gaseous pollutants. There were also a significant number of locations where the indoor air was deemed as "not acceptable" for these environments. About the same time a project carried out by the Istituto Centrale per il Restauro (Central Institute for Restoration, ICR), “The Risk Map of Cultural Heritage,” was just being completed. It was well known that air pollution and other factors were responsible for bringing about the degradation many items of historical significance. Monitoring was carried out for (among other things) suspended particulate matter, black smoke, sulfur dioxide, ozone and rain pH to directly define environmental aggressiveness and the rate of deterioration of the various cultural assets. Each single municipality was assigned a danger (risk) value or index with the aim of defining a hierarchy of the various phenomena according to their hypothetical effects. A correlation was observed between those locations with the highest risk factors and those not meeting reactivity monitoring standards. Closer examination of past and present reactivity monitoring data revealed that there were a number of locations where this correlation was not as close as one might have expected when compared to the Risk Map. It was suspected that the standard practice of “normalizing” reactivity monitoring results to a 30-day exposure period mayhave been artificially increasing the reported severity level – especially for exposure periods greater than 60 days. Using the same reactivity monitoring rates and acceptance criteria, a new environmental classification scheme has been developed using actual corrosion results and exposure times. This approach showed that the copper reactivity rates were being overstated more than 35% of the time with these longer monitoring periods. Since the original Museum Campaign, reactivity monitoring has continued for some of the same sites as well as a number of new sites. These results have shown higher average reactivity levels indicating that, if anything, air pollution levels in Italy are getting worse instead of better. If these trends continue, many cultural treasures may be lost or irreparably damaged. This paper will discuss past and present ERC monitoring results with respect to this new classification scheme. This with the intent of looking toward their use both as a standard gauge of outdoor and indoor air quality for museums, libraries, and archives as well as recommendations for their use as a general monitoring tool for the ICR and the Risk Map.