Probability of Significant Mold Exposure at Home

The prevalence of mold in US homes is surprisingly high. The Lawrence Berkeley National Laboratory estimated that about 47% of US homes have visible mold and/or dampness conditions. The WHO has identified indoor dampness and mold as significant risk factors for respiratory health problems.

Mold exposure is associated with allergic rhinitis, asthma exacerbation, hypersensitivity pneumonitis, and in immunocompromised individuals, invasive fungal infections. About 21% of asthma cases in the US are attributable to indoor dampness and mold exposure. The most common indoor molds include Cladosporium, Penicillium, Aspergillus, and Alternaria. Stachybotrys chartarum ("black mold") receives the most media attention but is actually less common than other species.

Professional mold remediation costs $1,500-$9,000 for moderate issues and $10,000-$30,000+ for extensive contamination. Homeowners insurance typically covers mold resulting from a covered peril (such as a burst pipe) but not mold from ongoing maintenance issues (like chronic leaks). Prevention includes maintaining indoor humidity below 50%, fixing leaks promptly, ensuring adequate ventilation (especially in bathrooms and kitchens), and using exhaust fans during cooking and showering.