Indoor/outdoor particulate matter concentrations and microbial load in cultural heritage collections

Abstract

Background: Particulate matter, microorganisms in air and environmental conditions present a potential risk to museum collections. There are also limited studies of simultaneous measurements of airborne particles and microorganisms inside museums and the effects of seasonal variations. Therefore, extensive indoor/outdoor measurements of particulate matter mass/number concentrations and viable, cultivable microbial load were performed in two museums and a library in Greece for a period of 2 years at selected time intervals. The culture heritage collections are located at coastal (Historical Museum of Crete in Heraklion), urban (Criminology Museum of the University of Athens) and mountainous (Neophytos Doukas Library in Zagori) environments and their collections consist mainly of organic materials. Measurements of inhalable particulate mass (PM 10 , PM 2.5 , PM 1) and viable, cultivable airborne microorganism concentrations (heterotrophic bacteria, cellulose metabolizing bacteria, acid producing bacteria and mesophilic fungi) in air were performed. Results and conclusions: The indoor PM 10 and microbial concentrations were higher than the outdoor levels showing the influence of the indoor sources, such as the presence of people and indoor activities, as well as, anthropogenic outdoor sources, and natural emissions. Elevated PM 1 particle number concentrations were also encountered in the Historical Museum of Crete in Heraklion and the Criminology Museum of the University of Athens due to the high anthropogenic emissions of the urban areas. The lowest concentrations of viable, cultivable airborne microorganisms were measured in the Historical Museum of Crete at the coastal site, which encounters also well controlled microclimatic conditions. In comparison to the other two naturally ventilated sites, the highest concentrations of viable, cultivable airborne fungi were measured in the Neophytos Doukas Library at the mountainous site, whereas the highest concentrations of viable, cultivable airborne heterotrophic bacteria were measured in the Criminology Museum of the University of Athens at an urban site, where mummified tissues and dry specimens are exhibited. The closed showcases of the two museums and the library could only protect the exhibits from viable, cultivable airborne fungi, but not from specific categories of bacteria. Acid producing bacteria in the Historical Museum of Crete, cellulose metabolizing bacteria in the Neophytos Doukas Library, and opportunistic pathogenic heterotrophic bacteria in the Criminology Museum of the University of Athens showed to be enriched inside the closed showcases.

Seasonal monitoring of microbiological air contamination from a museum - a case study

“…The high number of CFU/m 3 for all species in the present study confirms the findings of other researchers that the museum environment is favourable for the growth of microorganisms, ensuring conditions for survival and propagation an environment with high humidity and a nutrients [8], particularly the patrimony objects of textile and leather being a growth supportive substratum for developing moulds and bacteria [9,10]. According to the results of the quantitative analysis the recommended limits have been exceeded in almost all deposits but also in many of the rooms with full visitors access.…”

Fungi and Bacteria in Indoor Cultural Heritage Environments: Microbial-related Risks for Artworks and Human Health

“…In these environments, an inappropriate ventilating or air-conditioning systems may cause fluctuations of temperature and relative humidity. If the microclimate parameters are not stable, biological particles can evolve in a potential threat to objects and humans [6][7][8][9][10][11]. The exposure to some microorganisms, in particular Staphylococcus sp., thermophiles actinomycetes or mycetes, such as Aspergillus, Alternaria, Penicillium, Aureobasidium may induce illness as rhinitis, sinusitis, asthma or alveolitis in humans.…”

Seasonal Variation of Airborne Fungi of the Tiantishan Grottoes and Western Xia Museum, Wuwei, China

“…Recently, both culture-based methods and DNA-based molecular approaches such as clone library method based on 16S ribosomal DNA/RNA or ITS (Internal transcribed spacer) regions, PCR-DGGE, NGS (Next-Generation Sequencing) have been widely employed on biological identi cation of the airborne microbes in various historical sites [22][23][24]. Previous studies revealed that airborne microbial concentration and community composition varied greatly among heritage sites, particularly for indoor and outdoor of the museums [23,[25][26][27]. Meanwhile, the microbial concentration and community composition in the atmosphere are in uenced by various factors, mainly natural environment variation (e.g.…”