Biodeterioration of paper by fungi is one of the most important causes of damage occurring on library and archives collections. So far, over 580 fungal species responsible for biodeterioration of paper have been identified, and the species of Penicillium, Aspergillus and Alternaria genera are the most frequently associated with the destruction of deposited collections (Pinheiro et al., 2019). However, as one recent study showed, the extent of fungal contamination of paper documents stored in archives can be moderate and uneven (Cyprowski et al., 2022a).

Usually, the fungal growth is favoured by an increase of air humidity, which has been noted in archives and libraries by numerous authors (e.g. Borrego-Alonso et al., 2021; Karbowska-Berent et al., 2011; Pinheiro et al., 2012; Skóra et al., 2015). However, as the moisture content in the air of premises decreases, the strength properties of paper change (including shrinkage and stiffening as well as crushing of adhesives), which may contribute to the dust generation from the surface of collected documents (Valentín et al., 1998). As it has been shown, in the air in archives and libraries both PM10 and PM2.5 dust fractions are present (Pereira et al., 2017; Pinheiro et al., 2014), which, if deposited on floor or shelves, becomes a reservoir of numerous fungal species (Borrego et al., 2022). The studies have also shown that deposited dust can be resuspended due to the movement of people and their various activities, which result in an increase of fungal concentration in the air (Jürgensen & Madsen, 2016).

Significant daily fluctuations in the fungal concentrations were noted in several studies (Caicedo et al., 2023; Wu et al., 2021; Zielińska-Jankiewicz et al., 2008) and were usually associated with the occupational activity of workers in these institutions. It should be noted that besides few studies (Harkawy et al., 2011; Wlazło et al., 2008), stationary measurements with the use of impaction method were the most frequently used (Anaya et al., 2016; Caicedo et al., 2023; Karbowska-Berent et al., 2011; Micheluz et al., 2018; Zielińska-Jankiewicz et al., 2008). However, according to the available literature, the use of the filtration method in the form of personal measurements allows for a better characterization of occupational exposure to fungi during the work-shift, especially when high mobility and a wide range of activities were evaluated (Thorne et al., 2004; Toivola et al., 2004).

Recently, the methods of assessing the occupational exposure to fungi in various industries have also included the research on microbial contamination of the nasal cavity (Cruciani et al., 2022; Viegas et al., 2018, 2019). However, recognition of the upper respiratory tract contamination with microbiological agents has not so far been performed in the case of archive and library workers.

Considering the current state of knowledge, the aim of this preliminary study was to characterize the occupational exposure to inhalable dust and airborne fungi among archive and library workers using stationary and personal filter samples as well as nasal swab collected from them after the work-shift.

1 Materials and methods

1.1 Sampling sites

The study was carried out in 2020 and 2021 in the months from May to September and involved 3 archives and 2 libraries located in Poland. The general characteristics of these institutions are presented in Table 1. There was no visible mould or signs of water damage inside the studied rooms or on documents. In consultation with occupational health and safety specialists, a total of 22 stationary measurement points were established in the selected storage rooms. Due to the SARS-CoV-2 pandemic, out of all 72 people employed in these institutions, only 9 workers accepted their participation in the study.

Table 1 General characteristics of studied archives and libraries
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1.2 Bioaerosol sampling

All samples of airborne fungi were taken using CIS Sampler (Conical Inhalable Sampler, Casella Measurements Inc., UK) loaded with PTFE membrane filter (SKC Inc., USA) with a pore size of 2 µm and diameter of 37 mm. Each CIS sampler was connected with APEX pump (Casella Measurements Inc.) and placed on racks, 1.5 m above the floor or attached to clothing in the worker’s breathing zone. The flow rate of the air was set to 3.5 l/min, and the sampling was performed for about 6 h from 8 to 2 p.m., which accounted for 75% of the work-shift time. The applied sampling strategy allowed to take a total of 22 stationary and 9 personal air samples.

For determination of inhalable dust concentration, a gravimetric method was used. In the laboratory, the filters before and after the measurement were conditioned for 24 h in a controlled microclimate room (mean temperature = 20.0 °C; standard deviation, SD = 0.53; relative humidity = 33.3%; SD = 3.20) and weighed using microbalance XS-105DU (Mettler-Toledo GmbH, Switzerland), with accuracy of 10 µg.

Simultaneously with stationary bioaerosol measurements, at each sampling point, the temperature and relative humidity were measured in duplicates with the use of portable thermo-hygrometer Testo 410-2 (Testo SE & Co. KGaA, Germany). In total 44 measurements of each microclimate parameters were taken.

1.3 Nasal swab sampling

The study participants were instructed about the swabbing procedure, which protocol was approved by the Bioethics Committee of the Institute of Rural Medicine in Lublin, Poland (resolution No. 7 of May 28, 2020). Nasal swabs were collected after the work-shift. The sampling was performed by trained medical personnel, using nylon fibre sterile swabs with Amies medium (eSwab™, Copan Diagnostics Inc., USA). The swabbing procedure was as follows: in order to retrieve the swab sample, the worker’s head was gently tilted back and held by the chin. The moistened end of the sterile swab was placed in the right nostril of the worker, about 2 cm deep, and the swab was vigorously wound around the walls of the nostril five times. The same procedure using the new swab was repeated in the left nostril. Each swab with the collected material was then placed in a test tube with Amies medium and transported to the laboratory. In total, 18 nasal swab samples were obtained from archive and library workers.

In order to relativize the results obtained with this method, additional nasal swabs were collected from 5 office workers in a building not related to the institution participating in this study. In total, 10 samples for mycological analysis were taken in this way.

1.4 Identification of fungi

In the laboratory, filters were subsequently eluted with 5 ml of 0.9% NaCl aqueous solution, and then 0.2 ml of the suspension was picked and plated on microbiological MEA medium (Malt Extract Agar, BTL, Poland). Then, the plates were incubated under the following conditions: 4 days (30 °C) + 4 days (22 °C). Prolonged incubation of the samples was intended to capture both pathogenic and environmental species. After incubation, all growing colonies were counted and the fungal concentrations were expressed as colony-forming units per 1 cubic metre of the air (CFU/m3).

Nasal swabs were shaken vigorously for 15 min in tubes. Then, a series of tenfold dilutions in the range of 100–10–4 was prepared using 0.9% NaCl aqueous solution and Petri plates with MEA medium were inoculated with 1 ml of the suspension. After incubation, the obtained result was reported as CFU/ml.

The qualitative identification of fungi was made with the use of specialized keys (Samson & Frisvad, 2004; Samson et al., 2004; St-Germain & Summerbell, 2011). For the full taxonomic identification of yeast-like fungi, the biochemical API C AUX test (bioMérieux, France) was used to assess their ability to enzymatic degradation of organic substrates. The strains, which taxonomic identification was not reliable, were additionally analysed in Life Science Park (Krakow, Poland) using a MALDI-TOF mass spectrometer (Bruker Daltonics, Germany).

1.5 Statistical analysis

The obtained results were presented as arithmetic means (AM) with standard deviations (SD) as well as medians (Me) together with the concentration ranges. In the case when the subtraction values of the filter masses (before and after measurement) were equal to zero (40% of the results), these data were replaced with the values resulting from the statistical model. As all the independent variables were not normally distributed (based on Shapiro–Wilk test), the nonparametric Mann–Whitney (M-W) and Kruskal–Wallis (K-W) tests as well as Spearman’s rank correlation coefficient were used to confirm statistical importance of the observed relationships. The Chi-square test was also used to assess differences in fungal diversity. All calculations were performed using Statistica data analysis software system, version 10. (StatSoft, Inc., USA), assuming a value of p < 0.05 as statistically significant.

2 Results

The measurements carried out using CIS samplers showed the presence of both an inhalable fraction of dust and airborne fungi in this occupational environment (Table 2). Taking into account the results obtained in all institutions participating in the study, the average dust concentration was 49 µg/m3 (SD = 91), of which the highest one was found in archive No. 2 (152 µg/m3; SD = 170) and the lowest in library No. 2 (26 µg/m3; SD = 67). In the case of airborne fungi, the average concentration reached the level of 299 CFU/m3 (SD = 579). The highest fungal abundance was occurred in archive No. 3 (1771 CFU/m3; SD = 267), while the lowest in library No. 1 (97 CFU/m3; SD = 114). The comparative analysis did not show any significant differences in the concentrations of both variables, neither between particular institutions, nor between groups of archives and libraries. There were also no significant differences between objects with different types of air ventilation.

Table 2 Concentrations of inhalable dust and fungi in archives and libraries regarding study institution
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The obtained results showed that both inhalable dust and fungal concentrations were higher in the case of personal than stationary samples (Table 3). In most of the assessed cases, these differences were statistically significant.

Table 3 Concentrations of inhalable dust and fungi in archives and libraries regarding sample type
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The use of the nasal swab technique in employees of the studied institutions as well as in the control group showed high contamination of the nasal cavity in archive workers (Fig. 1). The median of fungal concentration was nearly 104 CFU/ml. It was significantly higher (H = 10.6; p < 0.01) than in library (1.4 CFU/ml) and office workers (0 CFU/ml).

Fig. 1
figure 1

Fungal concentrations in nasal swab samples among archive, library and office workers (control group). K-W test—Kruskal–Wallis test

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Simultaneously to the bioaerosol measurements, microclimate parameters were also examined. The average temperature value in all tested premises was 22.3 °C (SD = 1.73), ranging from 19.4 to 25.6 °C. In turn, the average value of relative humidity was 42.7% (SD = 6.30), ranging from 32.8 to 50.0%. The comparative analysis showed no significant differences in these parameters between archives and libraries.

The conducted correlation analysis showed strong relationships between the inhalable dust and airborne fungal concentrations (R = 0.57; p < 0.001). However, the performed calculations showed no significant correlations between the fungal concentrations in the noses and exposure to inhalable dust and airborne fungi. The relationships between the microclimate parameters and the concentrations of both dust and fungi in the air at workplaces were also not significant.

The mycobiota isolated in archives and libraries was characterized by high taxonomical variability depending on the source of the taken samples (Table 4). Considering the air samples, more abundant species diversity was present in archives than in libraries. In the archive premises, a total of 22 fungal species belonging to 14 genera were identified (17 moulds, 5 yeast-like fungi), while in the libraries 15 species from 10 genera (10 moulds, 5 yeast-like fungi) were found. However, these differences were not statistically significant. In turn, comparing the mycobiota isolated from nasal cavities, it turned out that 23 fungal species from 15 genera were present in archive workers, but only 8 species from 7 genera in participants from libraries. In this case, the observed difference was statistically significant (Chi-square = 13.57; p < 0.001). Significantly greater biodiversity was also found in the nasal swab samples of archive and library workers compared to the group of office workers (Chi-square = 43.51; p < 0.001). However, the biodiversity of fungi in the noses and those present in air samples was comparable (p > 0.05).

Table 4 Species composition and percentage contribution in relation to the total concentration of mycobiota in the air and in workers’ noses from the examined archives and libraries
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Among the airborne fungi, the widest spectrum of species was found in genera of Penicillium (8 species) and Aspergillus (3 species). Among the identified species, pathogenic A. fumigatus was present, with concentrations ranging from 15 to 73 CFU/m3. Moulds in libraries also accounted the largest percentage in relation to the observed concentrations (53.3%). However, in samples from archives, yeast-like fungi from Sporidiobolus and Candida genera (including pathogenic C. albicans) were present at higher concentrations than moulds in the range of 30–1540 CFU/m3. In turn, the mycobiota inhabiting the nasal cavity of archive and library workers was dominated by yeast-like fungi of Candida, Geotrichum, Cryptococcus and Sporidiobolus genera as well as dermatophytes—Microsporum and Nannizzia. Among the moulds present in the workers’ noses, strains of Penicillium and Talaromyces genera as well as the pathogenic A. fumigatus were isolated. However, the analysis showed that as many as 10 fungal species (including 8 moulds) were present both in air samples and in the noses of archive workers. In the library environment, such a situation concerned Candida and Cryptococcus yeast-like fungi only.

3 Discussion

This study was one of the few attempts to assess fungal contamination in archive and library environment using the filtration as bioaerosol sampling method. The results of the average fungal concentrations in two libraries we studied were comparable to those reported in twenty libraries in Upper Silesia (Wlazło et al., 2008), where in rooms with gravity ventilation the fungal levels reached the value of 149 CFU/m3, while in rooms with air conditioning—66 CFU/m3. In turn, using personal sampling in the library on Bright Hill, the concentration of airborne fungi was found to be 938 CFU/m3 (Harkawy et al., 2011). This higher-than-current level of contamination came from the study where sampling time was only 30 min, compared to 6 h in our project. However, according to the available research data, this should not have any effect on the decrease in viability of the isolated fungal strains (Durand et al., 2002).

Unfortunately, there are so far no similar measurement data from archive rooms, which until now were obtained using the impaction as a sampling method. Nevertheless, the concentrations of airborne fungi obtained in this study did not differ significantly from those noted in archives located in a similar climatic zone. In the study of Zielińska-Jankiewicz et al. (2008), the fungal concentrations ranged from 50 to 1200 CFU/m3, while in the work of Skóra et al. (2015) they did not exceeded 250 CFU/m3.

The concentrations of fungal aerosol measured in all libraries and archives in this study were lower than the threshold limit value proposed for workers’ protection by Expert Group on Biological Agents (EGoBiA) at the Polish Interdepartmental Commission for Maximum Admissible Concentrations and Intensities for Agents Harmful to Health in the Working Environment (Pośniak & Skowroń, 2022). For the archives’ premises, the safe fungal concentration was set at the level of 5000 CFU/m3. However, in this type of environment, apart from protecting the employees, archival collections should also be protected against microbiological contamination. For this reason, a reference value of 150 CFU/m3 has been proposed by EGoBiA for bacteria and fungi together. Taking into account the value of 150 CFU/m3, 10 out of 31 samples (32%) collected in the studied storage rooms exceeded this limit, suggesting that the collections may be at risk of microbial contamination.

This study showed that the fungal concentrations from personal measurements were significantly higher than those obtained using stationary measurements. Similar results have been reported earlier, which shows that in this type of work environment, the emission of fungal aerosol is strictly dependent on the specific activities performed by workers (Harkawy et al., 2011; Wlazło et al., 2008). This was also confirmed in the studies of Zielińska-Jankiewicz et al. (2008), who showed a high variability of fungal concentrations during 5 h of work and Karbowska-Berent et al. (2011) who observed that the levels of fungal contamination increased in the end of the work-shift.

It has been already proven that fungal conidia can colonize both stored collections (Borrego et al., 2012; Cyprowski et al., 2022a; Zielińska-Jankiewicz et al., 2008) and different elements of room equipment, such as walls, shelves, boxes as well as mobile trolleys, on which documents are transported (Pinheiro, 2014). Usually the presence of fungi on these surfaces is associated with the concept of settled dust (Borrego et al., 2022). When the collections become the subject of work, for instance, they are taken from the shelves and/or taken out of the archival stores, in order to read, share, preserve, archive (digitize) and bind, then these activities are accompanied by air movement, which initiates the phenomenon of resuspension of deposited dust and its floating in the air together with fungal conidia. This was proved by the study of Goebes et al. (2011), when fungal concentrations of Aspergillus genus were increasing during normal walking in a library.

In the current study, the inhalable dust in archives and libraries ranged between 3 and 336 μg/m3, of which 19% exceeded the limit value of 50 μg/m3, recommended by the ISO 11799:2015 standard; however, all these cases concerned samples from personal measurements. These results did not differ significantly from other studies of this type. For example, a research in four Portuguese archives showed that PM10 ranged between 4.43 and 285.5 μg/m3, with higher concentrations observed in the reading than in storage rooms (Pinheiro et al., 2014). More precise data on the spread of dust during the work of librarians were documented by real-time measurements (Baldelli et al., 2021). It showed that during conservation and repair, removing books from the shelves and unpacking donation boxes, PM10 concentrations may range between 200 and 300 μg/m3, while performing works such as dusting shelves, packing boxes, cataloguing books and photocopying generates dust at the level of 60–80 μg/m3. Moreover, these authors found that during the work with the highest dust emission, the highest fungal conidia concentrations of Penicillium and Aspergillus genera also occurred, in the range of 2000–9000 conidia/m3, and the correlation of these two parameters was R = 0.83. The significant correlation in our study between the inhalable dust and viable fungal concentrations at the level of R = 0.57 confirmed that the presence of dust was conducive to their development in this occupational environment. It is probable that the dust deposited on the surfaces of paper documents and shelves contained a large number of fungal conidia (but without visible growing) which, after rising into the air, were captured during measurements. Moreover, as shown by Adhikari et al. (2006) dust can provide nutrients for airborne fungi, which can facilitate their growth in conditions at optimal relative air humidity. The presence of dust in such concentrations can have a real impact on the health of employees. A study in Thailand libraries showed that at dust concentrations of 202 μg/m3, library workers had significantly higher prevalence of skin rashes than office workers (Chullasuk et al., 2016).

It is also extremely important that the microclimate parameters in the archives should be at an optimal level, i.e. the temperature should be 18 ± 2 °C, and the relative air humidity 50 ± 3% (ISO 11799:2015). In the studied institutions, 81% of temperature results were above, and 63% of the humidity results below the recommended values, which means that the environment was characterized by a rather dry microclimate. Such conditions are conducive to weakening the durability of the paper document structures (Olejnik & Wysocka-Robak, 2005; Sequeira et al., 2019). With an increase in air humidity above 65%, the paper may become a place for the growth of fungi, thus contributing to the biodeterioration of paper documents (Caneva et al., 1991). Our results indicate that the microclimate was not suitable for fungal growth in studied institutions. Fungal spores were present in large quantities, probably due to deposition from the air or previous contamination. It was shown that some fungal species release their conidia only when air humidity decreases, which may result in increased fungal concentrations in air samples (Troutt & Levetin, 2001; Madsen, 2012).

The spread of fungal contamination due to the occupational activity of archive and library workers was reflected in the analysis of nasal swab samples. Data on mycobiota in the upper respiratory tract of this group of workers should be considered pioneering. This increasingly popular method of assessing the exposure to bioaerosols in various industries (Viegas et al., 2017) confirmed more convincingly that fungal exposure in archives was much higher than in libraries. Fungal contamination of the nasal cavity among archive workers was found to be two orders of magnitude higher than those of library and office workers. Although it was not possible to reveal significant relationships between airborne fungi and those deposited in the noses of employees, it should be recalled that this project was carried out during coronavirus pandemic, which significantly limited the possibilities of obtaining volunteers for research. To obtain higher certainty regarding the observed phenomena, it would be advisable to perform such measurements on a larger group of workers in the future. This would give higher statistical power of the study.

Till now, quantitative data obtained from swab samples describing the fungal contamination of the nasal cavity of employees should be considered extremely scarce. A kind of exception was a study conducted on a group of greenhouse workers, when the fungal contamination was assessed using the nasal lavage technique (Madsen et al., 2013). It was then shown that the median concentration of fungi in the noses was 75 CFU/ml and their presence was highly dependent on the airborne fungi at the workplaces. The literature available so far, in which nasal swabs were used for the qualitative identification of fungi concerned employees of the paper industry (Niemelä et al., 1985), cork industry (Viegas et al., 2019), poultry farms (Cruciani et al., 2022) as well as veterinarians (Viegas et al., 2018) and health professionals (Viegas et al., 2021). According to the knowledge available to the authors in this regard, it was for the first time confirmed that 45% of the fungal species identified in the air occurred also in the nasal cavity of archive and library workers. Despite the small number of people participating in the study, it does not seem that the obtained result was a coincidence. There were no significant differences in the biodiversity of fungi inhabiting the nasal cavity and the air in the studied premises. It seems that a future study evaluating across-shift changes in the composition of mycobiota could provide more information on the impact of this work environment on fungal contamination of respiratory system of employees in libraries and archives, as was the case with the exposure of waste incineration plant workers to bacterial aerosols (Cyprowski et al., 2022b).

According to Pasquarella et al. (2012) each such environment is so specific that a detailed analysis of both the fungi and the conditions in which they occur is necessary. Some researchers believe that the mycobiota in archives and libraries is sometimes dominated by cellulolytic fungi, the presence of which is associated with paper biodeterioration. This includes, for example, moulds of Chaetomium, Trichoderma and Stachybotrys genera (Pyrri et al., 2020). However, in the currently analysed working environments, only single Trichoderma colonies have been identified and instead a high percentage of yeast-like airborne fungi was found, which in the case of storage rooms in archives exceeded 50% of mycobiota. Compared to other studies, this percentage seems to be quite high, as, for example, in the libraries in Venice it was about 40% (Micheluz et al., 2018), in the library with limited access on Bright Hill—28% (Harkawy et al., 2011), while in the libraries studied by Karbowska-Berent et al. (2011) it amounted to only 1.38%. The presence of yeast-like fungi in the studied interiors, on the one hand, indicates their anthropogenic origin, as they can inhabit various areas of the human body, including the skin and nasopharynx (Belvoncikova et al., 2022; Sellart-Altisent et al., 2007). On the other hand, these fungi can also be isolated from the atmospheric air, from where they could have entered the study rooms through natural ventilation (Adams et al., 2013). However, according to the available studies, yeasts from Candida and Cryptococcus genera can produce cellulolytic enzymes responsible for the biodegradation of paper, which allows them to colonize documents stored in archives and libraries (Leite et al., 2012; Pinheiro, 2014). It is therefore probable that these fungi penetrated the nasal cavity of the employees during working with such contaminated documents.

Among the yeast-like fungi isolated from the air, special attention should be paid to Candida albicans pathogenic species. As the study in Vilnius libraries showed, this fungus may be an important component of the mycobiota in this occupational environment (Lugauskas & Krikštaponis, 2004); however, according to the available data, C. albicans is the predominant species isolated from all age groups of healthy people (Alizadeth et al., 2021), what means that these people are carriers without reporting specific symptoms, but in enclosed spaces they become emitters of these yeast-like fungi. Recent reports in this area suggest that this fungus often coexists with the bacterial pathogen Staphylococcus aureus, contributing to the formation of dual-species inter-kingdom biofilm in the upper respiratory tract (Kean et al., 2017). Additionally, it should be noted that C. albicans is one of the most frequently isolated species from patients diagnosed with systemic mycosis, including fungal rhinosinusitis (de Oliveira Santos et al., 2018; Tilak et al., 2012). Another pathogen detected in the nose of one of the archive worker was a dermatophyte from Microsporum genus. Its presence may suggest that this person may have had contact with a pet (cat or dog). Fungi of this genus are responsible for numerous mycosis of the skin, nails and hair (Segal & Elad, 2021). Due to the described pathogenic properties, the mentioned genus Microsporum and C. albicans species have been classified in the list of harmful biological agents in the Commission Directive (EU) (2019) in the second risk group.

In the studied archives and libraries, high biodiversity of moulds was found, among which a special attention should be paid to the species of genus Aspergillus, including A. fumigatus. Their presence in high concentrations is generally considered negative for the health of exposed persons. The concentrations of this fungus found in the current study were not high and did not differ significantly from the levels usually observed in samples of atmospheric air (O’Gorman, 2011). Unfortunately, due to the filter sampling technique used, it was impossible to obtain background samples within 6 h. For this reason, there are no data on the possible infiltration of ambient fungi into the tested interiors through the ventilation system. Nevertheless, under favourable conditions, fungi of the Aspergillus genus have the ability to produce various types of volatile organic compounds or harmful mycotoxins (Nielsen, 2003), and Aspergillus fumigatus is characterized by strong infectious activity contributing to the development of pulmonary aspergillosis (Latgé, 1999). The threat from this species for studied archive and libraries workers does not seem to be high; however, according to the CDC (2003) recommendations, due to the possible negative health effects of A. fumigatus concentration, it should be kept to a minimum. For all these reasons, the entire Aspergillus genus as well as A. fumigatus species, were included in the list of harmful biological agents according to the Commission Directive (EU) (2019) in the second risk group.

Many fungal species identified in the archive rooms are microorganisms that naturally inhabit soil, plants and polluted water. Nevertheless, some of them including Alternaria, Aspergillus, Mucor, Penicillium, Paecilomyces, Talaromyces or Trichoderma genera have the ability to produce enzymes such as: lipase, protease, cellulase or amylase, which accelerate decomposition of paper, enabling them to biodeteriorate this type of material (Anaya et al., 2016; Borrego et al., 2017; Pinheiro, 2014).

Moreover, most of the identified moulds have allergenic properties which may cause allergies and irritations (Borrego & Molina, 2018). The fungal allergens and toxins can be present in viable strains, but also in dead conidia as well as mycelial fragments, which could not be detected by culture-based analysis. In order for the risk assessment to be comprehensive, other analytical techniques should be included, e.g. determination of β-glucan concentrations (Sigsgaard et al., 2005). However, despite this limitation, the results obtained in this study should be seriously considered in terms of health protection. As it was shown by Gambale et al., (1993) among 314 employees of the São Paulo library, 49% of the respondents reported the presence of long-term symptoms of rhinitis and asthma, of which 80% noticed that these symptoms intensified at the workplace. Furthermore, approximately 17% of employees performed positive skin tests for fungal allergens, including e.g. Acremonium, Fusarium, Penicillium, Geotrichum, Rhizopus and Rhodotorula genera.

4 Conclusions

This study confirmed that archives and libraries are occupational environments, in which exposure to fungi is obvious and common. However, it has been shown that their abundance increased with the growth of inhalable dust concentration in the air. Moreover, for the assessment of occupational exposure to bioaerosol, the use of personal sampling appeared to be a more efficient collection technique than stationary measurements. The nasal swabbing applied in the study showed that airborne fungi were able to efficiently contaminate the nasal cavity of employees. This method can be considered as an important analytical approach to support the assessment of workers’ exposure to bioaerosols. Nevertheless, it is advisable in the future to confirm the observed relationships in a larger study population, supplementing this type of research with assessment of respiratory and skin complaints reported by archive and library workers.