Fungal Fragments as Indoor Air Biocontaminants

Abstract

The aerosolization process of fungal propagules of three species (Aspergillus versicolor, Penicillium melinii, and Cladosporium cladosporioides) was studied by using a newly designed and constructed aerosolization chamber. We discovered that fungal fragments are aerosolized simultaneously with spores from contaminated agar and ceiling tile surfaces. Concentration measurements with an optical particle counter showed that the fragments are released in higher numbers (up to 320 times) than the spores. The release of fungal propagules varied depending on the fungal species, the air velocity above the contaminated surface, and the texture and vibration of the contaminated material. In contrast to spores, the release of fragments from smooth surfaces was not affected by air velocity, indicating a different release mechanism. Correlation analysis showed that the number of released fragments cannot be predicted on the basis of the number of spores. Enzyme-linked immunosorbent assays with monoclonal antibodies produced against Aspergillus and Penicillium fungal species showed that fragments and spores share common antigens, which not only confirmed the fungal origin of the fragments but also established their potential biological relevance. The considerable immunological reactivity, the high number, and the small particle size of the fungal fragments may contribute to human health effects that have been detected in buildings with mold problems but had no scientific explanation until now. This study suggests that future fungal spore investigations in buildings with mold problems should include the quantitation of fungal fragments.Water damage in buildings is common and is often associated with mold problems. In North America, cross-sectional questionnaire studies have found that 27 to 36% of homes have mold problems (9, 51). Studies that included indoor air quality measurements have shown even higher numbers, from 42 to 56% (8, 11). In Europe, the prevalence of damp and moldy homes has been reported to be 17 to 46% for Great Britain (5,23,34,42), 15 to 18% for The Netherlands (3, 55,56), and 15% for Finland (41). Alarmingly, signs of present or previous moisture-related defects were found in 80% of randomly selected private homes investigated by civil engineers trained to recognize the signs of water leaks or condensation (37).Increased prevalence of water-damaged buildings and subsequent fungal contamination may contribute to the noted increase in allergic diseases. Fungi can affect human health in a variety of ways. Possible reactions generally fall into one of three groups: allergic reactions (sensitization and immune responses, i.e., asthma, allergic rhinitis, or hypersensitivity pneumonitis), infections (growth of the fungus in or on the body, e.g., aspergillosis), and toxic responses (24,30,45). The toxic reactions are mainly connected with the secondary fungal metabolites, i.e., mycotoxins, but the role of cell wall components, such as ␤-(133)-D-glucans, has also been reported (4,26,29,45,47,50). In addition, expos...

Performance of an Electrostatic Precipitator with Superhydrophobic Surface when Collecting Airborne Bacteria

“…Respiratory symptoms, febrile episodes, allergic diseases such as hypersensitivity pneumonitis, and asthma due to bioaerosol exposure have been documented among workers employed in waste industry (Chiba et al 2009;Poulsen et al 1995). It was also found that not only viable, but also non-viable bioaerosol particles are capable of causing adverse health effects (Adhikari et al 2009;Gorny et al 2002;Robbins et al 2000).…”

Fungal fragments in moldy houses: A field study in homes in New Orleans and Southern Ohio

“…This method is limited typically to particles >1 μm (Green et al, 2006). Recent laboratory-based studies (Górny et al, 2002 andCho et al, 2005) have reported that large quantities of submicrometer-sized fungal and actinomycete fragments (ranging from 30 nm to 1 μm) are released together with intact spores from contaminated surfaces. These studies demonstrated that the number of released fragments was always higher, up to 500 times, than the number of intact spores.…”

“…Smaller-sized fragments have longer lifetimes in the air compared to larger spores and can penetrate deeply into the alveolar region when inhaled. Fungal fragments have been shown to contain fungal antigens (Górny et al, 2002), mycotoxins (Brasel et al, 2005a, b), and (1→3)-β-D-glucan (Seo et al, 2007). The small size, large quantities, and biological properties of fungal fragments suggest that these particles may potentially contribute to the adverse health effects and raises the need for further characterizations of fungal fragments in moldy buildings.…”

Targeted Inspection of Environmental Mycological Load for Mitigation of Indoor Mold toward Improved Public Health

“…Indoor molds may fragment into very small airborne mycotoxincontaining particles, resulting in an up to 500-fold higher exposure than previously assumed [13,[88][89][90]. In addition, Cho et al [91] showed that the respiratory deposition of S. chartarum fragments is over 200-fold higher than that of spores in adults and an additional 4 to 5 times higher in infants.…”

“…Some methodologies go beyond the fungal spore-borne toxin counts by determining indoor mold fragments in very small, airborne, mycotoxin-containing particles, resulting in an up to 500-fold higher exposure level than previously assumed [13,[88][89][90].…”