Written by: Jorissia Barnett
Within commercial buildings and homes, indoor air quality (IAQ) is often overlooked until visible indicators or physical symptoms are seen. Evidently, mold is one of the prime culprits responsible for poor IAQ. Among the vast types of mold, Aspergillus is one of the most common and toxic fungal genera found indoors.
The genus Aspergillus contains several species, of which some are opportunistic pathogens that can cause infection. For instance, Aspergillus fumigatus is the most common cause of pneumonia in individuals with a weakened immune system (immunocompromised), while others such as, A.niger and A.flavus are invasive to humans (Stokes & Rajasekaran, 2008). The success of Aspergillus’ pathogenicity is achieved through allergens, mycotoxins, volatile organic compounds (VOCs) and adaptation.
Allergens - An allergen is a foreign substance that triggers an exaggerated immune response in sensitive persons, commonly known as an allergic reaction. Fungal spores are common allergens that can intensify allergies when produced in high concentrations, especially for people with asthma and rhinitis. Regarding Aspergillus, several common indoor species including A.niger and A.oryzae are considered to be allergic, and have been associated with exacerbated asthma attacks in adults.
Mycotoxins – Mycotoxins are toxic secondary metabolites produced by fungi including Aspergillus that can result in disease and death. Aspergillus secretes well known mycotoxins such as ochratoxin A and aflatoxin which restrict the immune system in fighting infection and permits mold colonization.
VOCs - These include aldehydes, ketones, alcohols, esters, sulfur and nitric compounds that are products derived from the synthesis processes within the microorganisms. Common Aspergillus species such as A.fumigatus, A.sydowii and A.flavus produce these compounds that can result in headaches, dizziness and inattentiveness, to name a few. At lower concentrations, these symptoms can be felt more easily in immunocompromised individuals such as asthmatics, and in drastic cases these metabolites can even be found in the breath of some patients.
Adaptation – The ubiquitous nature of Aspergillus facilitates its proliferation in various environments. Its versatile features such as hydrophobicity, melanin and thermotolerance for example, allow for a more efficient spore dispersal, higher environmental protection and an easier vertebrate infection and colonization within the respiratory tract (Mousavi, 2016).
Therefore, due to the prominent health risk Aspergillus imposes, the indoor fungal ecosystem is one that should be carefully monitored and always regulated. For most indoor air quality problems, especially within homes, source control is the most effective solution. This can be achieved through regular indoor air quality testing which permits proactive measures that reduce toxins and pollutants to facilitate a healthier indoor environment (Lewis, 2022).
References
Gautam, A. (2013). Characterization of Aspergillus species associated with
commercially stored triphala powder [Photograph]. African journal of
Biotechnology, 11, 16814-16823. 10.5897/AJB11.2311
Stokes, D., & Rajasekaran, S. (2008). Respiratory Infections in
Immunocompromised Hosts [Review of Respiratory Infections in
Immunocompromised Hosts]. In L. Taussig (Ed.), & L. Landau (Trans.), Pediatric Respiratory Medicine (Second Edition) (pp. 555–574). Mosby.
https://www.sciencedirect.com/science/article/pii/B9780323040488500402
Mousavi, B. (2016). Aspergillus species in indoor environments and their
possible occupational and public health hazards. Current Medical Mycology, 2(1), 36–42. https://doi.org/10.18869/acadpub.cmm.2.1.36
Aspergillus Mold in The Home ......Health Problems, Treatment, Removal. (2019). Mold Advisor. https://www.mold-advisor.com/aspergillus-mold.html
Lewis, T. (2022, June 8). We Need to Improve Indoor Air Quality: Here’s How and Why. Scientific American. https://www.scientificamerican.com/article/we-need-to-improve-indoor-air-quality-here-rsquo-s-how-and-why/
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