The Hidden Health Risks of Musty Odours: What Mould and MVOCs Mean for Your Home
- Relief Restorations
- Oct 11
- 6 min read
Introduction
That familiar musty smell in a basement, crawlspace, or bathroom is more than just unpleasant, it’s a warning sign. Musty odours often mean that mould is present and actively releasing gases known as microbial volatile organic compounds (MVOCs).
While many people dismiss the smell as “old house air” or just dampness, these odours signal that something more serious could be affecting the health of your home and everyone living inside.
Understanding the connection between mould, MVOCs, and indoor air quality is crucial. Left untreated, mould growth not only damages property but also contributes to respiratory issues, allergic reactions, and long-term health conditions. Recognizing musty odours as an early indicator of hidden mould can help you act before problems become severe.
Section 1: What Are MVOCs?
When mould grows indoors, it doesn’t just spread spores, it also releases gases as it digests organic material such as wood, drywall, or paper backing on insulation. These gases are called microbial volatile organic compounds (MVOCs). They are similar in name to volatile organic compounds (VOCs), which are chemical emissions from paints, cleaning products, and other man-made materials, but MVOCs are biological in origin.
MVOCs are responsible for the characteristic musty odours that people often associate with damp basements, old buildings, or areas with hidden leaks. They are composed of tiny molecules that easily evaporate into the air, making them easy to inhale and difficult to avoid once released indoors. Because MVOCs are a byproduct of active mould metabolism, their presence almost always points to ongoing growth somewhere in the home.
Unlike visible mould, which is easy to spot, MVOCs can exist even when mould is hidden behind walls, under flooring, or in attics. That’s why musty odours are such an important warning sign, by the time you smell them, mould is already releasing gases into your living environment.
Section 2: How MVOCs Affect Indoor Air Quality
MVOCs are extremely small and light, which means they can spread quickly throughout a building. In spaces with poor ventilation, such as basements or sealed attics, these gases build up, saturating the air and causing persistent musty odours. Even after surface cleaning, MVOCs can linger in the environment if the underlying mould and moisture sources are not addressed.
Because of their volatile nature, MVOCs mix easily with indoor air and can travel far beyond the original contamination site. For example, odours from mould in a basement can move upward through ductwork or cracks in flooring, eventually affecting the entire home. This wide distribution is part of what makes microbial odours so disruptive, they are difficult to contain without proper remediation.
More importantly, MVOCs impact indoor air quality in ways that go beyond smell. Breathing in these compounds can irritate the respiratory system, trigger allergic reactions, and contribute to headaches or fatigue. People with asthma, allergies, or other sensitivities often notice symptoms worsen in environments where musty odours are present. Over time, consistent exposure to MVOCs may increase health risks, particularly for children, seniors, and those with weakened immune systems.
Section 3: Health Risks of MVOCs
Immediate Health Effects
For many people, exposure to musty odours and MVOCs causes irritation soon after entering the affected space. Symptoms may include:
Sneezing, coughing, or throat irritation
Watery or itchy eyes
Headaches or dizziness
General fatigue
These reactions are the body’s natural response to airborne irritants. For sensitive individuals, even low levels of MVOCs can make a noticeable difference in comfort and wellbeing.
Respiratory Issues
MVOCs can also aggravate the lungs and airways, especially in those with asthma or other respiratory conditions. Inhaling mould-related compounds can:
Trigger asthma attacks
Cause wheezing and shortness of breath
Worsen seasonal allergies
Lead to persistent coughing or chest tightness
Children and older adults are particularly vulnerable since their immune and respiratory systems may not respond as effectively to airborne pollutants.
Long-Term Concerns
The longer MVOCs remain in your indoor environment, the greater the potential health impact. Chronic exposure has been linked to more serious conditions, including Chronic Inflammatory Response Syndrome (CIRS), a complex illness associated with mould exposure. While not everyone develops long-term issues, the risks are significantly higher for individuals with compromised immune systems. This is why addressing musty odours promptly is more than just a matter of comfort, it’s a health priority.
Section 4: Where Do Musty Odours and MVOCs Come From?
Mould and MVOCs thrive in environments that provide moisture, organic material, and poor ventilation. Common problem areas in homes include:
Basements and crawlspaces – prone to dampness and hidden leaks
Bathrooms – condensation and insufficient ventilation encourage mould growth
Attics – roof leaks or inadequate air circulation can create hidden mould colonies
Kitchens and laundry rooms – moisture from daily activities creates ideal conditions
Behind walls and under flooring – plumbing leaks or past water damage may allow mould to grow unnoticed
In many cases, HVAC systems also spread musty odours throughout the home, moving MVOCs far from the original contamination site. This explains why a musty smell in one area often seems to permeate the entire house.
Section 5: How to Address MVOCs and Mould Odours
Professional Inspection
Because MVOCs signal active mould growth, professional testing and inspection are the most reliable ways to identify the problem. Restoration specialists can conduct moisture surveys, air sampling, and visual inspections to locate hidden mould sources.
Moisture Control
Since mould cannot thrive without moisture, stopping water intrusion is critical. This may involve repairing plumbing leaks, improving ventilation, or using dehumidifiers to keep humidity below 50%.
Mould Remediation
Once identified, mould-contaminated materials such as drywall, insulation, or carpeting must be safely removed. Proper containment and personal protective equipment (PPE) prevent spores and MVOCs from spreading during cleanup. After removal, the area is disinfected and dried to prevent regrowth.
Air Quality Improvements
Even after remediation, odours may linger if airborne MVOCs remain. Restoration professionals may use:
HEPA air scrubbers to capture spores and odour molecules
Negative air machines to exhaust contaminated air outside
Safe deodorization methods such as hydroxyl or ozone treatments (applied only under controlled, unoccupied conditions)
These measures ensure the air is safe to breathe and that odours do not return.
Conclusion
Musty odours should never be ignored. They are one of the clearest signs that mould is present and actively releasing MVOCs into your living space. Beyond the unpleasant smell, these compounds can trigger allergies, worsen asthma, and contribute to serious long-term health issues.
By recognizing odours as early warning signs and taking action, through moisture control, professional inspections, and safe remediation, you can protect both your home and your health.
If you’ve noticed persistent musty odours in your home, Relief Restorations can help. Our certified team specializes in mould inspections, air testing, and remediation, ensuring your space is safe, clean, and comfortable again.
Contact Relief Restorations Today
Schedule a mould air test, moisture survey, asbestos testing, remediation, inspection or consultation with our team to ensure your home is protected. Let us help you safeguard your home and restore peace of mind, knowing that you’re in good hands.
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Water Damage – Restoration | Content Services | Moisture Surveys
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At Relief Restorations, we specialize in providing comprehensive restoration services, including mould remediation, water damage restoration, fire and smoke damage restoration, asbestos removal, light demolition, inspection and testing services across Winnipeg and Manitoba, Canada.
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