Indoor mould likely contributes to considerable yet under-quantified health loss from asthma, COPD, and respiratory infections, with significant implications for healthcare costs and productivity. This study quantifies the prospective health benefits, cost savings, and income gains of eradicating indoor mould in Australia. Key model inputs include the prevalence of moderate (16.5%) and severe (11.0%) indoor mould and its estimated causal associations with asthma incidence, chronic respiratory disease severity, and lower respiratory tract infection incidence. Health-adjusted life years (HALYs), healthcare costs, and income changes impacts were estimated in a sophisticate proportional multistate lifetable model discounted at 3% annually. Eradicating indoor mould led to 4,190 (95% UI 1920 to 7350) HALYs gained per million people alive in 2021 over the next 20 years (or about 1.5 healthy days per person). The most deprived quintile experienced 1.66 times the benefit observed in the least deprived quintile. Health expenditure in the next 20 years decreased by US$78.0 million per million people (95% UI 34.6 to 138), equivalent to 0.5% to 2.1% of total health spending in a year. Income in the next 20 years increased by US$116 million (95% UI 48.7 to 219) per million people, equivalent to 0.08% to 0.36% of Australia's 2021 GDP. Health gains from mould eradication appear to be approximately three times greater than those from eliminating cold housing and comparable to other well-established preventive health interventions. Future research should prioritize reducing uncertainty in mould-related health risks and evaluating cost-effective housing interventions such as ventilation retrofits.

The authors have declared no competing interest.

This study was supported by the NHMRC Centre of Research Excellence in Healthy Housing (APP1196456; principal investigator [CI] Rebecca Bentley, Melbourne School of Population and Global Health, University of Melbourne) and NHMRC Ideas Grant (APP2004466; principal investigator [CI] Rebecca Bentley, Melbourne School of Population and Global Health, University of Melbourne). The funder of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report.

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This study used de-identified data from the Australian Housing Conditions Dataset 2022 (AHCD22), published through the Australian Data Archive (DOI: 10.26193/SLCU9J). As the dataset is publicly available and fully deidentified, the research was exempt from human research ethics approval, in accordance with institutional and national guidelines for secondary analysis of non-identifiable data.

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