Summary of the 2025 Systematic Review for Non-Specialists & Patients

Read full paper here: Potential respiratory hazards of fungal exposure in the residential indoor environment: a systematic review – ScienceDirect

What was this review about?

This review looked at all the scientific evidence from 1990–2025 on how indoor fungi (moulds) in homes affect people’s breathing and general respiratory health. It examined 94 studies, mapping out where fungi come from, which species appear most often, and how they affect the lungs, nose, throat, and immune system.

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Key Findings in Plain Language

1. The biggest sources of indoor mould are dampness and building damage

Homes with water leaks, damp walls, damaged materials and poor ventilation are the most common sources of fungi—especially Aspergillus and Penicillium. These thrive in wet building materials, bathrooms, kitchens, drains, air-conditioning systems and even water dispensers.

2. Indoor fungi are strongly linked to a wide range of respiratory symptoms

Across many countries, indoor fungal exposure was associated with:

• Asthma and asthma flare-ups

• Allergic rhinitis (blocked or runny nose)

• Chronic cough and throat irritation

• Adenoid enlargement in children

• Hypersensitivity pneumonitis (allergic inflammation of the lungs)

• Reduced lung function

• Even pulmonary haemorrhage in rare cases

The review shows that even everyday exposure—not just visibly mouldy homes—can worsen respiratory health.

3. Some fungi are more strongly associated with illness

Important associations include:

• Aspergillus → asthma symptoms, COPD exacerbations, throat irritation, hypersensitivity reactions

• Penicillium → asthma, allergic rhinitis, hypersensitivity pneumonitis

• Alternaria → childhood asthma risk

• Candida & Fusarium → present in wet areas such as bathrooms and may affect vulnerable individuals

4. The geographic picture is uneven

Most research comes from high-income, temperate countries. There are major evidence gaps in tropical and subtropical regions, where humidity is high and fungal exposure is likely worse. This limits current global understanding of risk.

5. Prevention works — but public awareness is low

Simple actions (cleaning, improved ventilation, addressing leaks, correct humidity ranges) can radically reduce fungal burden. One study showed 80–90% reduction in airborne mould counts after residents were given basic remediation advice.

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What’s New or Important in This 2025 Review?

1. A fully integrated “source → species → disease → location” map

The review is the first to link fungal sources, the exact fungi found, the diseases they cause, and where the evidence comes from, creating a multi-layered evidence map. This helps identify:

• Which household features pose the highest risk

• Which fungi are clinically most important

• Where research gaps exist

2. Highlights the major global research imbalance

It emphasises that very little evidence exists from low-income and tropical areas—where exposure may be far more severe. This is a call for equity and better global surveillance.

3. Shows that fungi may affect more than the lungs

The review notes new evidence that fungal exposure may also influence neurological and immune-mediated symptoms, suggesting mould exposure could have broader health effects than traditionally recognised.

4. Identifies major gaps in identifying which fungal species cause harm

Many studies only measure “mould level” without identifying the fungus. The review argues for better fungal detection technologies, such as:

• Portable real-time samplers

• Multi-omics (DNA, RNA, metabolites)

• Long-term cohort studies

These tools could finally clarify which fungi cause which illnesses.

5. Strong emphasis on emerging technologies for prevention

Including:

• UV and photocatalytic TiO₂ devices

• Improved antifungal cleaning agents

• Building materials designed to resist mould growth

• Volcanic minerals and clays that absorb harmful compounds

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Why This Review Matters (for Patients, Carers, and Clinicians)

1. It shows mould is not “just an allergy problem”

Indoor fungi can worsen or trigger asthma, COPD, hypersensitivity pneumonitis, chronic sinus issues, and may even influence immune and neurological health. This validates patient experiences where damp homes worsen symptoms.

2. It provides strong evidence for housing-related health advocacy

Patients can use this to:

• Request landlord repairs

• Support home assessments

• Advocate for rehousing if severe mould is present

• Justify humidifier/dehumidifier use, and ventilation improvements

3. It highlights the importance of early remediation

Even simple cleaning and remediation steps can dramatically reduce mould burden and symptoms—important for families, vulnerable groups, and those with chronic lung disease.

4. It gives clinicians a clearer evidence base

Respiratory teams can use this to:

• Recognise when housing contributes to disease flare-ups

• Understand which conditions are most strongly linked to indoor fungi

• Make better-informed referrals for environmental health assessments

5. It builds a scientific foundation for future guidelines

The authors point out that national building codes, indoor air quality policies, and public health guidance lag behind the evidence—and this review is intended to inform future regulation.

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Who Does This Help Most?

Patients with:

• Asthma

• Allergic bronchopulmonary aspergillosis (ABPA)

• Aspergillus bronchitis

• COPD (especially those with fungal-associated exacerbations)

• Hypersensitivity pneumonitis

• Children with recurrent respiratory infections

• Anyone living in damp, mouldy, water-damaged, or poorly ventilated homes

Clinicians:

Respiratory physicians, GPs, ENT specialists, allergists, immunologists.

Policy & Housing Professionals:

Public health teams, environmental health officers, social landlords, housing associations.

Researchers:

Those developing diagnostics, fungal exposure studies, indoor air quality monitoring, or patient-centred environmental interventions.

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