A Review: Fungal Exposure Assessment in Indoor Environments

Abstract

While the fungal exposure assessment was based on the determination of fungal propagules for a long time, recent progress has led to the development of methodology for other fungal agents, e.g. the fungal cell wall components, metabolites, and allergens, that may be responsible for health effects caused by fungal exposure. This review includes a summary of the sampling techniques and analytical methods that are currently used or are in progress for the fungal exposure assessment. Prospects for the future trends are also discussed. In the future, the development will focus on sampling techniques that allow longer sampling times, a higher sampling efficiency for relevant particle sizes, and better possibilities for a wide range of analyses. In addition, new or modified methodology based on chemical, immunochemical, and molecular biological techniques to measure fungal agents related to health effects will improve the understanding of biological responses caused by fungal exposure.

Assessment of Fungal Contamination in Moldy Homes: Comparison of Different Methods

“…The results of this study support previous reports that this reliance might grossly underestimate the number of spores present in a sample, which might potentially lead to an underestimation of the severity of mold contamination. (26) The culturability of spores is dependent on a number of factors, including spore type, temperature, and type of agar. Furthermore, since culturability is not generally linked to allergenic respiratory symptoms, these symptoms may still occur when the culture-based enumeration technique generates results below the limit of detection.…”

“…The culture-based analysis, which is more common, gives the ability to identify colonies to the species level and a large reference database is available for proper identification of colonies. (26) Species-level identification is useful in detecting "indicator fungi" that are commonly found in moldy buildings. For many years, the culture-based methods have tended to be the dominant choice of both the practicing indoor air quality professionals and the research community since the Andersen sampler was used as "the gold standard" for bioaerosol sampling.…”

“…Furthermore, it might underrepresent those fungal types that grow slowly because they are overtaken by faster growing colonies. (26,(28)(29)(30)(31)(32) Kozak et al (33) demonstrated that although the level of culturable spores may be below the limit of detection, the total number of spores may be sufficient to cause respiratory symptoms.…”

“…Among disadvantages of this enumeration method, there are (a) masking effect, when the background matrix may mask small spores; (b) high data variability when spore density is low; (c) overestimation of large pigmented spores; and (d) impossibility of performing the species-level identification. (26,36) Other methods for fungal analysis include the use of surrogate markers that measure quantitative loads of fungal biomass, such as β-glucan and ergosterol. These indicator methods are useful for providing general information about the total amount of fungi in the environment but are often not specific enough to relate to health outcomes because of their surrogate nature.…”

Culturability and concentration of indoor and outdoor airborne fungi in six single-family homes

“…Modern technology provides the investigators with a variety of ways for analyzing fungi while each method has certain advantages and drawbacks (Pasanen, 2001). Many studies utilized culture-based analysis as well as total spore analysis using optical microscopy.…”