Why Home Mould Inspection is Critical for Preventing Hypersensitivity Pneumonitis: Insights from the Latest Research

As clinicians and environmental health experts know, hypersensitivity pneumonitis (HP) is a serious lung disease often triggered by chronic exposure to airborne antigens, with indoor moulds being an especially important culprit. While HP can lead to permanent lung damage and even death, recent research further strengthens the case for vigilant home mould inspection and proactive remediation. In this blog, we’ll draw on compelling findings from a large new academic study published in PLOS One in 2025, focusing on what it means for patients with respiratory sensitivity and the importance of thorough, professional home mould assessments—such as those carried out by Biological Health Services.

What is Hypersensitivity Pneumonitis and Why Does Home Mould Matter?

Hypersensitivity pneumonitis is an immunologically mediated lung disease that occurs in susceptible individuals after inhaling environmental antigens. In everyday environments, these antigens are often found in mould and fungal spores growing inside homes, particularly in areas affected by water leaks or persistent dampness. HP can be either acute or progress to a chronic, fibrotic form, causing permanent lung injury if not managed early.

Historically, home mould has been underestimated as a cause of HP, in part due to difficulties in exposure characterization and the high background prevalence of visible mould. However, HP is relatively rare, and the literature has been limited by relatively small numbers and lack of detail about specific mould sources.

Hypersensitivity pneumonitis (HP) is an inflammatory lung condition triggered by the body’s immune reaction to inhaled environmental antigens, most often found in dust, organic particles, or mould fragments present in homes and workplaces. When susceptible individuals repeatedly breathe in mould spores and fragments—especially those arising from chronic water damage or damp conditions—HP can develop, leading to symptoms like persistent cough, breathlessness, and fatigue. Over time, ongoing exposure may cause irreversible lung scarring and significant breathing difficulties. The latest research highlights that home mould exposure is a significant and often underrecognized cause of HP, emphasizing that mould growth—sometimes hidden in bathrooms, bedrooms, or air conditioning systems—can have profound health consequences . Recognizing and remediating mould sources in living environments is therefore essential not only for preventing HP but also for protecting overall respiratory health.

New Evidence Linking Home Mould Exposure to Lung Disease

A major new retrospective cohort study published in 2025 provides the strongest evidence yet for the link between home mould exposure and hypersensitivity pneumonitis1. This study, conducted in north Texas, examined 231 HP patients treated between 2011 and 2019. Of these, mould exposure inside the home was confirmed as the cause in 54 patients (over 23% of the total HP cases).

Key Findings from the Study

Home Mould as a Major Cause: 54 of 231 HP patients (23.4%) were found to have home mould as their primary antigenic exposure. The majority of these exposures resulted from chronic or recurring water intrusion—such as leaking pipes, roof leaks, and unremediated water damage.
Severity of Illness: Nearly 90% of these cases were fibrotic, the most severe form of HP, highlighting that chronic exposure can lead to lasting lung damage if not addressed early.
Locations of Mould Growth: The most common places for mould growth in affected homes were the bathroom, bedroom, and central air conditioning units. A significant portion of patients had visible mould in multiple areas of their homes.
Benefits of Exposure Removal: Among patients who eliminated exposure—either through professional remediation or moving house—over 12% saw a significant (>10%) improvement in lung function within 3-4 months, and none deteriorated after exposure was removed. While improvement is less likely in fibrotic cases, some patients with established lung scarring still benefited, underlining that it’s never too late to act.
Survival: Survival outcomes for HP from home mould were similar to those from mould or avian antigen exposures outside the home, reinforcing the seriousness of domestic mould as a risk factor1.

Home Mould Can Hide—And Is Frequently Overlooked

The study also noted that only 37% of affected patients had a professional mould inspection; most relied on patient or contractor confirmation. Importantly, many patients had more than one area with visible mould, and several had complex or chronic water problems that allowed hidden fungal growth to linger.

For clinicians and environmental experts, this underscores a critical issue: Visual inspection and professional assessment are superior to casual or superficial checks. The study emphasizes that a history of water intrusion provides strong evidence for the possibility of mould overgrowth, even when not visible on the surface1.

The Special Problem of Trichosporon (and Why You Need the Right Testing)

A crucial global lesson comes from Japan, where "summer-type" hypersensitivity pneumonitis is common and is frequently attributed to the yeast Trichosporon species. These organisms can thrive in damp environments, especially in the humid months, and cause HP in genetically susceptible individuals. Notably, Trichosporon does not always produce the large spores or visible fungal structures that are picked up by traditional spore trap air samples or basic surface tests.

Only viable sampling methods—where live microorganisms are cultured and identified—are effective for detecting Trichosporon species. Spore trap methods, which are popular but limited, can easily miss these yeasts, leading to false reassurance1. This is a key reason Biological Health Services favours best-practice assessment methodologies, including sampling for both viable and non-viable organisms, coupled with a thorough exposure history.

This principle extends beyond Trichosporon: Many pathogenic moulds and fungi (and even bacteria) can persist in hidden, moist environments behind walls, under floors, or inside ductwork, escaping everyday detection until they cause illness.

Mould Inspections: A Vital Tool for Protecting Lung Health

The 2025 study makes one message clear: Anyone experiencing unexplained respiratory issues—especially those with a diagnosis of hypersensitivity pneumonitis—should have a professional mould inspection of their home. Not only does this identify possible sources of ongoing antigen exposure, but proper remediation or even moving out of the affected property can lead to real clinical improvement.

Professional home inspections, including detailed exposure assessments and viable sampling, bridge the gap between incomplete visual checks and real preventive healthcare. They are especially critical for sensitive groups such as:

People with chronic respiratory symptoms (cough, shortness of breath, wheeze)
Individuals with pre-existing lung conditions (asthma, COPD, or HP)
Anyone living in a home with a history of water leaks or poor ventilation
Healthcare professionals looking to support patients with unexplained interstitial lung disease

Practical Tips: What Should a Homeowner (or Healthcare Provider) Do?

Get Proactive: If you have unexplained respiratory symptoms, don’t wait. A home inspection may be vital to your diagnosis and ensuring the best possible recovery.
Insist on Quality Testing: Choose inspectors who use viable sampling methods, know how to detect hidden damp and mould, and understand the risks from less common organisms like Trichosporon—not just visible mould.
Act on Findings: If mould is discovered, remediation by professionals is crucial. Sometimes, the only suitable action is to move out, especially if remediation isn’t possible.
Monitor Lung Health: Work with your healthcare provider for appropriate follow-up, and repeat mould assessments if symptoms persist or recur.

Why Biological Health Services?

At Biological Health Services, we are committed to best-practice, science-guided inspections—employing sophisticated methodologies tailored to the needs of sensitive individuals. Our approach is informed by the latest international evidence, including comprehensive case studies like the 2025 PLOS One study, and recognizes that "invisible" sources of home mould must be actively sought and professionally managed.

Conclusion

Hypersensitivity pneumonitis is a serious, sometimes life-altering condition, but it is also a reminder of the importance of environmental vigilance. The newest research supports what clinicians and environmental experts have long observed: Home mould is a significant, modifiable risk factor for chronic lung disease, and professional inspection is an essential part of diagnosis and prevention. If you or your patients are at risk, don’t leave mould in the dark—call us at Biological Health Services for an expert, thorough assessment.

This blog post is informed by the latest peer-reviewed scientific literature to support patient care and environmental health decision-making. For more information or to schedule a consultation, visit our website or contact our team today.