Black Mould

Black mould, scientifically known as Stachybotrys chartarum, is a household hazard that often hides in plain sight. It thrives in damp, humid environments and can pose serious health risks to individuals and families. 

What is Black Mold?

Black mould is a type of fungus that can appear as greenish-black and slimy. It is commonly found in areas with high humidity and moisture, such as under seats, especially child seats, on seatbelts, and in the boot of your car. Black mould may not always present itself with visible signs, making it a hidden threat. This is especially the case in cars which often have black interiors, meaning you are more likely to smell the problem before you see it.

As with all toxins, it's the dose makes the poison. As a car is a small, confined space, this means black mould is a particular hazard in vehicles as you may be exposed to more concentrated levels of the mould spores.

Health Risks Associated with Black Mold

Exposure to black mould can have adverse health effects, especially on the respiratory system. The mycotoxisn produced by this mould can lead to symptoms such as coughing, wheezing, throat irritation, nasal stuffiness, skin rashes, and eye irritation. In severe cases, it can trigger asthma attacks, bronchitis, or other respiratory issues. Vulnerable groups, including individuals with weakened immune systems, children, and the elderly, are at higher risk of experiencing these health problems.

Common Signs of Black Mold Infestation

Identifying signs of black mould in your vehicle is crucial. Musty odours, visible mould growth (which may vary in appearance), and unexplained health issues could be indicators of a black mould problem. Addressing any water leaks, moisture problems, or condensation in your car promptly can help prevent black mould growth.

Dealing with Black Mold

If you suspect a significant black mould infestation, it is essential to consult a professional.

Disturbing black mould can release spores into the air, potentially exacerbating the problem and posing health risks. While there are DIY mould removal methods, tackling black mould without the proper equipment and expertise is not recommended.

Conclusion

Black mould may be a hidden threat, but understanding its dangers is crucial for maintaining a safe and healthy vehicle. You are likely to be able to smell it before you can see it, so be very aware of damp, musty smells when you enter your vehicle. Being vigilant about identifying and removing black mould in your car can help protect your family's well-being. Seek expert advice when dealing with significant mould issues to ensure the safety of yourself and loved ones.

References:

NHS UK. (2022). Mould and Damp in Your Home.
Health and Safety Executive (HSE). (2022). Mould at Work. 
Mayo Clinic. (2022). Black Mold Exposure: What It Is and Isn't.

What it means

Black mould is a fungus that grows where moisture has been trapped. In cars it shows up as dark spots or fuzzy patches on carpets, seat bases, underlay, soundproofing and even seatbelts and trims. It thrives in damp, poorly ventilated areas such as soaked footwells, under seats, in spare wheel wells and inside box sections or cross members that have held water. It is a clear sign that the car has had a leak or flooding and that the interior has not dried quickly enough.

Why it matters

• Health and comfort concerns: Mould releases spores and can aggravate breathing issues, allergies and general discomfort for people in the car. Even if you feel fine, passengers might not.
• Persistent musty odours: Black mould is a major cause of that damp, stale smell that returns as soon as you switch off the air freshener. Odour normally will not go away until the underlying mould and damp are dealt with.
• Shows deeper contamination: Visible mould on the surface often means the foam and underlay underneath are also affected. Simply wiping the top will not fix what is happening underneath.
• Impacts value and safety: A mouldy interior suggests neglected water damage. Over time this can be associated with corrosion to seat mounts, belts, wiring and box sections, affecting both value and long-term safety.

Where you will see it

You will see black mould mentioned in leak reports, water damage estimates and interior decontamination notes. Typical comments include black mould present on carpets and underlay, mould growth in rear footwells, mould contamination to soundproofing, recommend removal and replacement or heavy mould in spare wheel well and boot trims. It is common on cars that have had long-term leaks, blocked drains or have been stored damp for extended periods.

Context

Black mould sits in the middle of the water damage story. First there is a leak – from doors, rear vents, sunroof drains, scuttle, membranes or other points – then materials become wet and stay wet. If the car is not properly dried and decontaminated, mould appears and spreads, feeding on dirt, dust and organic material in carpets and foams. A professional response is to find and stop the leak, lift carpets and trims, remove or treat contaminated materials, dry the structure thoroughly and then refit or replace what cannot be saved. Simply shampooing the visible carpet or spraying deodoriser over the top leaves the underlying problem in place.

Common mistakes

• Trying to hide black mould with air fresheners, wipes or perfume instead of tackling the leak and damp materials causing it.
• Cleaning only the visible carpet fibres and leaving soaked, mouldy underlay and foam in place underneath.
• Assuming a warm summer will “dry it out” naturally, when thick soundproofing can stay wet and mouldy deep down for months.
• Refitting trims and seats over mould-affected areas without proper decontamination, allowing spores and odours to return shortly afterwards.

Written by Danny Argent. Last updated 09/12/2025 03:05