A review on inorganic gaseous pollutants in indoor spaces housing cultural collections

The preservation of cultural collections is directly and indirectly affected by environmental conditions (both climate and pollution). If the monitoring of climate conditions is becoming a common practice and regolated by EU standards and guidelines, gaseous air pollution concentrations are rarely monitored in indoors. For this reason, the present contribution aims at providing a scientific literature review on gaseous inorganic pollutants monitored in spaces housing cultural collections. To the best of our knowledge, such a review has not been conducting so far. Sixty-six scientific articles were selected through the PRISMA methodology (Page et al., 2021) over the period 1984-2021 for a total number of 80 case studies mainly located in Europe (64%). The monitoring was mainly performed in museums and galleries (61%), specifically in exhibition rooms (79%). Active devices were rarely employed, whereas passive samplers, exposed in situ and then laboratory-analysed, were mostly used for nitrogen dioxide and sulphur dioxide monitoring. Direct-reading continuous devices were widely used for ozone. It was found that average concentrations of ozone were below 5 ppb in only 50% of cases, nitrogen dioxide below 10 ppb in more than 60% of cases, nitrogen monoxide below 5 ppb in 30% of cases, nitric and nitrous acid below 1 ppb in less than 50% of cases, sulphur dioxide below 2 ppb in more than 60% of cases, hydrogen sulphide below 0.1 ppb in only 25% of cases. The lowest concentration values were usually associated with the use of mechanical ventilation systems equipped with air filters and with non-urban case studies. The low number of scientific articles and case studies can be due to the difficulties to perform monitoring in spaces housing cultural collections with the features of current sensors, usually developed for outdoor air pollutants measurements. References: Page, M. J., McKenzie, J. E., Bossuyt, P. M., Boutron, I., Hoffmann, T. C., Mulrow, C. D., Shamseer, L., Tetzlaff, J. M., Akl, E. A., Brennan, S. E., Chou, R., Glanville, J., Grimshaw, J. M., Hróbjartsson, A., Lalu, M. M., Li, T., Loder, E. W., Mayo-Wilson, E., McDonald, S., … Moher, D. (2021). The PRISMA 2020 statement: An updated guideline for reporting systematic reviews. The BMJ, 372, 1–9. https://doi.org/10.1136/bmj.n71