An examination of the emission of carboxylic acid from cultural heritage collections dependence on temperature - can a decrease in temperature reduce the demand for air filtration?

Preservation of cultural heritage collections for future generations place a large demand on air quality in exhibitions, repositories and display cases. Emission of harmful contaminants inside enclosures can be largely avoided by selecting suitable construction materials; however, the emission of contaminants from chemical decay process within the collections cannot be removed. Museum objects made of wood, paper and cellulose acetate emits carboxylic acids causing deterioration e.g. tarnishing of metals, salt efflorescence on calcareous structures, and acid hydrolysis of organic materials. The emission of formic and acetic from four naturally aged cultural heritage objects was determined using emission chambers with active sampling on silica gel and ion chromatography analysis. The results confirm that the emission depend on temperature. For example, the emission of carboxylic acids from a newspaper from 1914 decreases at 10°C to 68% of the emission rate at 23°C.
Growing concern for global climate changes together with budget restrains have led to an increasing replacement of energy consuming ventilation systems with repositories using a larger degree of passive control e.g. unheated repositories. The low temperature in unheated repositories will reduce the chemical deterioration and the emission of harmful contaminants from the collection. In this presentation, we will, by using a simple mass balance model compare the effect of temperature on the concentration of formic and acetic acid in air inside repositories. Based on the results the decrease in concentration when reducing the temperature from 23°C to 10°C will be estimated.
The results will be linked to existing guidelines for climate conditions and air quality in repositories. Reducing the emission of carboxylic acids from the collections with decreasing temperature will potentially reduce the requirement for air filtration and increase energy efficiency.