Water vapour as a carrier of mould metabolites in indoor air: an explanation for the sick building syndrome and severe morbidity

Vaali, K, Sulyok, M, Louhelainen, J ORCID: 0000-0001-8680-8614, Mannerström, M, Heinonen, T, Krska, R, Räsänen, LA, Visala, A, Harmo, P and Salkinoja-Salonen, M (2026) Water vapour as a carrier of mould metabolites in indoor air: an explanation for the sick building syndrome and severe morbidity. Science of the Total Environment, 1047. ISSN 0048-9697

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Abstract

Indoor air quality (IAQ) is a possible but unproven culprit for sick building syndrome (SBS). We earlier showed that emitted mould exudates are carried into ambient air by water clusters. When nine students (7–12 years) moved from the damaged school to reference schools, their symptoms attenuated but reappeared, within the same day, when transferred to schools with known IAQ problems. A self-made experimental recording of glass chambers and sensors of volatile organic compounds (VOC) and non-volatiles, relative humidity, CO2 and CN/sulphide were applied to mimic IAQ of the school. Mortar samples of the damaged school wall, when cultured on malt agar, grew alternative oxidase fungi (aox-fungi), which emitted exudates. Exudates were analysed by LC-MS/MS and tested on human BJ cells. LC-MS/MS analysis of the cultivated mortars showed that the mould-derived droplets hanging underneath culture lids transferred in water, being the same as the exudates' contents on top of mould growths. Boric acid added to the mortar cultivation, promoted the emission of mould metabolites, which were shown to be lethal to BJ cells. The results support presence of aox-fungi in the mortars, which was closest to the damaged area of the building. Cytotoxicity of the mould exudates in cultivation varied time-dependently, within two weeks, as indicated by BJ cells. The present results and earlier reported cytotoxic water vapour of this school air are the contact points between the mould exudates, damaged building and clinical symptoms: the missing link in the mystery of SBS. Analysing water vapour will reveal piggy-bagged toxic substances.

Item Type:	Article
Uncontrolled Keywords:	Indoor air quality; Mycotoxins; Non-volatile compounds; Symptoms; Volatile organic compounds; Water vapour; 33 Built Environment and Design; 3302 Building; 34 Chemical Sciences; Environmental Sciences
Subjects:	Q Science > Q Science (General) R Medicine > RS Pharmacy and materia medica T Technology > TH Building construction
Divisions:	Pharmacy and Biomolecular Sciences
Publisher:	Elsevier
Date of acceptance:	30 June 2026
Date of first compliant Open Access:	20 August 2026
Date Deposited:	20 Aug 2026 14:39
Last Modified:	20 Aug 2026 14:39
DOI or ID number:	10.1016/j.scitotenv.2026.182020
URI:	https://researchonline.ljmu.ac.uk/id/eprint/29174

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