Indoor fungal diversity and asthma: a meta-analysis and systematic review of risk factors
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Updated: May 12, 2026
Collection and Extraction of Occupational Air Samples for Analysis of Fungal DNA
Published on: May 2, 2018
Richard A Sharpe1, Nick Bearman2, Christopher R Thornton3
1European Centre for Environment and Human Health, University of Exeter Medical School, Truro, United Kingdom.
Background:
Indoor dampness increases the risk of indoor fungal growth. A complex interaction between occupant behaviors and the built environment are thought to affect indoor fungal concentrations and species diversity, which are believed to increase the risk of having asthma, exacerbation of asthma symptoms, or both. To date, no systematic review has investigated this relationship.
Objective:
This review aims to assess the relationship between exposure to indoor fungi identified to the genera or species level on asthma outcomes in children and adults.
Methods:
Ten databases were systematically searched on April 18, 2013, and limited to articles published since 1990. Reference lists were independently screened by 2 reviewers, and authors were contacted to identify relevant articles. Data were extracted from included studies meeting our eligibility criteria by 2 reviewers and quality assessed by using the Newcastle-Ottawa scale designed for assessment of case-control and cohort studies.
Results:
Cladosporium, Alternaria, Aspergillus, and Penicillium species were found to be present in higher concentrations in homes of asthmatic participants. Exposure to Penicillium, Aspergillus, and Cladosporium species were found to be associated with increased risk of reporting asthma symptoms by a limited number of studies. The presence of Cladosporium, Alternaria, Aspergillus, and Penicillium species increased the exacerbation of current asthma symptoms by 36% to 48% compared with those exposed to lower concentrations of these fungi, as shown by using random-effect estimates. Studies were of medium quality and showed medium-high heterogeneity, but evidence concerning the specific role of fungal species was limited.
Conclusion:
Longitudinal studies assessing increased exposure to indoor fungi before the development of asthma symptoms suggests that Penicillium, Aspergillus, and Cladosporium species pose a respiratory health risk in susceptible populations. Increased exacerbation of current asthma symptoms in children and adults were associated with increased levels of Penicillium, Aspergillus, Cladosporium, and Alternaria species, although further work should consider the role of fungal diversity and increased exposure to other fungal species.
Insights
Indoor fungi like Aspergillus and Penicillium are linked to asthma symptoms and exacerbation in children and adults. This review highlights their respiratory health risks, emphasizing the need for further research on fungal diversity.
Area of Science:
- Environmental Health
- Mycology
- Pulmonology
Background:
- Indoor dampness promotes fungal growth, potentially impacting respiratory health.
- Occupant behaviors and the built environment influence indoor fungal levels.
- Existing research lacks a systematic review on indoor fungi and asthma outcomes.
Purpose of the Study:
- To systematically review the relationship between exposure to specific indoor fungi and asthma outcomes.
- To assess the impact of fungal genera and species on asthma in children and adults.
Main Methods:
- Systematic search of ten databases (post-1990) and reference lists.
- Independent screening and data extraction by two reviewers.
- Quality assessment using the Newcastle-Ottawa scale for cohort and case-control studies.
Main Results:
- Higher concentrations of Cladosporium, Alternaria, Aspergillus, and Penicillium species found in homes of asthmatics.
- Exposure to Penicillium, Aspergillus, and Cladosporium linked to increased asthma symptom reporting.
- These fungi increased asthma exacerbation by 36%-48% in affected individuals.
Conclusions:
- Penicillium, Aspergillus, and Cladosporium species pose respiratory risks to susceptible populations.
- Increased indoor fungal levels correlate with asthma exacerbation in children and adults.
- Further research should explore fungal diversity and other species' roles in asthma.
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