Black mould isn't a cosmetic problem. It's a respiratory hazard. The NHS, the Department of Levelling Up, and the coroner's report into Awaab Ishak's death all say the same thing: prolonged mould exposure causes real harm, especially to children, the elderly, and anyone with asthma or weak immunity.
This guide explains: what mould actually does to your body, what Awaab's Law means for tenants and landlords, and — crucially — how to get rid of it for good. Anti-mould paint won't fix it. Neither will scrubbing with bleach. The cause has to go.
What black mould does to your body
The most common indoor mould is Aspergillus or Cladosporium. The much-feared Stachybotrys chartarum ("toxic black mould") is rarer but does occur in chronically damp UK homes. All three release spores that you breathe in continuously when present.
The NHS lists these confirmed health effects of prolonged mould exposure:
- Respiratory infections — bronchitis, sinusitis, persistent coughs
- Asthma flares — both new-onset asthma in children, and worsening in existing asthmatics
- Allergic reactions — runny nose, itchy eyes, skin rashes
- Increased susceptibility to chest infections
- Worsened eczema particularly in children
- Long-term: weakened immune response in vulnerable groups
The most vulnerable: children under 5, adults over 65, anyone with asthma or COPD, immunosuppressed people (cancer treatment, HIV, post-transplant), and pregnant women.
Awaab's Law — what it actually says
In December 2020, two-year-old Awaab Ishak died from a severe respiratory condition caused by prolonged mould exposure in his social-housing flat in Rochdale. The coroner's report concluded the mould was the direct cause of death. His parents had reported the issue to the landlord repeatedly. Nothing was done in time.
Awaab's Law (passed 2023, taking phased effect 2024-2025) requires UK social-housing landlords to:
- Investigate damp / mould reports within 14 days
- Begin repair work within 7 days of confirming the issue
- Treat "emergency" mould cases (where health is at immediate risk) within 24 hours
- Provide alternative accommodation if work cannot be safely done with the tenant in place
Tenants whose landlords fail can take them to court for compensation. Private landlords aren't yet covered by Awaab's Law specifically, but the Homes (Fitness for Human Habitation) Act 2018 already gives private tenants similar legal recourse.
For homeowners — Awaab's Law doesn't apply directly, but the same health risks do. If you have mould, the responsibility to fix it is yours.
Why scrubbing and painting doesn't work
The single biggest mistake homeowners make: treating mould as a surface problem.
Black mould lives where two conditions meet: moisture (humidity above 70%) and a food source (typically the cellulose in plaster, paint, wallpaper paste, MDF). Spores are everywhere in the air, indoors and out. The mould grows wherever those two conditions exist.
Scrub with bleach and the visible mould dies — for now. Wipe it clean and the surface looks fine — for now. Paint over it with anti-mould paint and you've added a chemical barrier — for a while. But the moisture is still there, the food source is still there, the spores are still in the air. The mould comes back, often within months.
The only permanent fix is to remove the moisture cause.
The two real causes of UK mould
In 90%+ of UK homes, mould is caused by either condensation (warm humid air hitting cold surfaces) or rising/penetrating damp (water in the structure). The fixes are completely different — get the diagnosis right or you waste money fixing the wrong thing.
For the diagnostic test, see our guide: Condensation vs Rising Damp — How to Tell the Difference.
If it's condensation (most common)
Mould around windows, in corners, behind wardrobes, on bathroom ceilings — that's condensation. Caused by too much moisture in your indoor air (cooking, breathing, showers, drying clothes indoors) hitting cold surfaces and condensing.
The fix: PIV (Positive Input Ventilation). A small loft-mounted fan replaces humid air with filtered fresh air whole-house, continuously, for £15-£25/year electricity. Indoor humidity drops below 60%, mould stops growing, existing mould dies off when cleaned. Single install, £900-£1,400 fitted, lasts 15+ years.
Read more: How PIV ventilation works · PIV vs dehumidifier comparison.
If it's rising or penetrating damp (less common but more serious)
Mould at the bottom of internal walls, with tide marks and crumbling plaster, is rising damp — water from the ground climbing up through brickwork. Mould on a wall after rain (dries out in summer, comes back in winter) is penetrating damp — water coming through external walls.
The fix for rising damp: chemical DPC injection + replastering, £800-£3,500. The fix for penetrating damp: external pointing repair / render / gutter fix, variable. Take our 2-minute damp self-check for severity rating.
Cleaning mould safely (while you fix the cause)
You'll still need to clean visible mould while the permanent fix is being installed. The NHS guidance:
- Wear an FFP3 mask, gloves, and goggles
- Wipe with a soapy cloth (not bleach — bleach kills surface mould but leaves the dead spores intact, which still cause allergic reactions)
- Wash all soft furnishings (curtains, bedding, clothes from affected areas) at 60°C+
- Throw away porous items that can't be cleaned (mouldy carpets, mattresses, wallpaper)
- Don't dry brush, vacuum without a HEPA filter, or use a fan — all spread spores
- Ventilate the area thoroughly during and after cleaning
Then fix the cause within weeks. Cleaning without fixing the cause = the mould is back in 4-12 weeks.
What to do this week
If you have mould in your home and someone in the household has asthma, eczema, persistent coughs, or is a child / elderly / immunocompromised — this is urgent. Don't let it slide.
- Take our 60-second condensation check — tells you whether PIV ventilation is likely the right fix. Run it free →
- Clean visible mould safely using NHS guidance above (this is short-term).
- Book a free 30-minute survey — we diagnose the cause properly, recommend the right fix, give you a fixed-price quote on the spot. Book a free survey →
- If you rent — report the issue to your landlord IN WRITING (email is best, keep the receipt). Awaab's Law (social housing) and Homes Fitness Act (private renting) both give you legal teeth.
Mould fixed permanently. Health protected.
60-second condensation check or 30-minute on-site survey — both free.
Sources: NHS guidance on damp and mould (nhs.uk); Department of Levelling Up, Housing and Communities — guidance on Awaab's Law; Coroner's Inquest into the death of Awaab Ishak (2022). This article is informational, not medical or legal advice. If symptoms are severe, see a GP. If you're a tenant in a mouldy home, contact Citizens Advice or Shelter.