That answer comes from NHS guidance on damp and mould, not from us. What we add, from surveying damp and mouldy homes across London and Surrey every week, is the practical side: what the risk actually depends on, when you can deal with it yourself, and why it so often comes back after cleaning.

What health problems can black mould cause?

Inhaled mould spores can trigger allergic reactions — sneezing, itchy eyes, skin rashes — and can worsen asthma. The NHS also notes a higher likelihood of respiratory infections in people living in damp, mouldy homes. The reaction is dose-dependent: a small patch on a bathroom ceiling is a different situation from a bedroom wall that stays wet all winter.

Who is most at risk from black mould?

Babies and children, older people, people with existing respiratory conditions such as asthma or COPD, people with skin conditions like eczema, and anyone with a weakened immune system. If someone in an affected room falls into one of those groups, treat the mould as a priority rather than a cosmetic job.

Can black mould kill you?

Severe outcomes are rare, but they are real. The death of two-year-old Awaab Ishak in 2020, from respiratory failure linked to prolonged black mould exposure in his home, is the reason Awaab’s Law now sets legal repair timescales for social landlords. For most healthy adults black mould is a health irritant rather than a mortal danger — but prolonged exposure in vulnerable groups is exactly what the law was written to prevent.

Can I remove black mould myself?

For a small area — as a rule of thumb, less than about one square metre on a hard surface — careful cleaning with a suitable fungicidal product is reasonable, with gloves, ventilation and no dry brushing (that releases spores). Larger areas, mould that returns within weeks, mould inside cupboards or on cold external walls, or any mould where a vulnerable person sleeps: that is the point to get it investigated properly.

Why does mould keep coming back after cleaning?

Because cleaning removes the symptom, not the cause. Mould grows where moisture persists — from condensation, a hidden leak, or rising or penetrating damp — and it will keep returning until that moisture source is found and fixed. This is the single most common thing our surveyors see: a wall repainted three times while the leak behind it was never traced.

When should I call a professional?

If the mould covers a large area, keeps returning, or affects someone in a risk group, book a proper investigation. Our surveyors take calibrated moisture readings, use thermal imaging to find the moisture source, and put the findings in a written report — useful for your own records, and essential if you are a tenant reporting to a landlord or a landlord who needs to show you acted. Mould investigations start with a survey (a flat £150, whatever the property size,); treatment is quoted once the cause is identified. See our mould treatment and removal service for how the full process works.