Mould and water damage in the home: health effects and what to do

Damp refers to excess moisture in a building, from sources such as condensation, leaks, rising or penetrating damp, or flooding. Mould is a fungus that grows where there is moisture. UK government guidance on damp and mould explains that excessive moisture can promote the growth of microorganisms such as mould and other fungi, certain species of house dust mites, bacteria or viruses.

After a flood or a major leak, materials can stay wet for a long time. The guidance stresses that the more serious the damp and mould problem and the longer it is left untreated, the worse the health impacts and risks are likely to be.

The guidance says damp and mould can produce allergens, irritants, mould spores and other toxins that are harmful to health. Most people come into contact with these by breathing them in, so the airways and lungs are mainly affected, and the effects can cause serious illness and, in the most severe cases, death.

It lists the respiratory effects: general symptoms such as cough, wheeze and shortness of breath, an increased risk of airway infections including aspergillosis, and the development or worsening of allergic airway diseases such as rhinitis, asthma and other airway inflammation conditions including bronchitis, hypersensitivity pneumonitis and COPD.

The guidance says that in 2019 the presence of damp and mould in English homes was estimated to be associated with approximately 5,000 cases of asthma and approximately 8,500 lower respiratory infections among children and adults, and with 1 to 2% of new cases of allergic rhinitis. Self-reported data suggest the percentage of dwellings affected may be higher, in which case the number of cases could be 3 to 8 times greater.

The inquest into the death of Awaab Ishak concluded that his death resulted from a severe respiratory condition due to prolonged exposure to mould in a home with inadequate ventilation, which the guidance cites as an example of why such problems must be acted on with urgency.

The guidance lists groups that are more vulnerable to significant health impacts, for whom damp and mould should be addressed with particular urgency.

• People with pre-existing conditions such as allergies, asthma, COPD, cystic fibrosis, other lung diseases and cardiovascular disease.

• People of all ages with a weakened immune system, such as those with cancer or having chemotherapy, transplant recipients and those taking medicines that suppress the immune system.

• People living with a mental health condition.

• Pregnant women, unborn babies and women who have recently given birth.

• Children and young people, whose organs are still developing.

• Older people, and people who are bedbound, housebound or have mobility problems.

For tenants the first step is to report the problem to the landlord or housing provider in writing, with dates and photographs. The guidance says landlords should respond with urgency, identify the severity and risks, tackle the underlying causes, and should not delay action to await medical evidence, because medical evidence is not a requirement for action.

It also explains that tenants cannot be expected to reduce moisture levels if their home does not enable them to do so, and that the root causes are building deficiencies, inadequate ventilation or low indoor air temperature. Practical suggestions in its tenant annex include cooking with pan lids on and keeping internal doors shut when cooking and bathing. Landlords should inspect at least 6 weeks after remedial work to ensure the problem has not returned.

If a landlord does not act, tenants can contact the local council's environmental health team, which has powers under the Housing Act 2004 and the Environmental Protection Act 1990 described in the guidance.

The guidance advises that anyone concerned about the symptoms they are experiencing should consult a healthcare professional. Persistent cough, wheeze, breathlessness or worsening asthma at home should be reviewed by a GP, and the GP can be told about the damp or mould so that it is considered as a possible factor.

Severe breathlessness, difficulty speaking in sentences, blue lips, or a baby or child who is struggling to breathe is an emergency and needs a 999 call.

Health problems are dealt with by GPs and NHS services. The housing problem itself is a matter for the landlord or owner and, where necessary, the local authority, which can inspect and take enforcement action. Homeowners are responsible for repairs and may use qualified surveyors and damp specialists, whose certifications are described in the guidance.

The guidance stresses that tackling the underlying causes, such as building deficiencies, inadequate ventilation and condensation, matters more than removing surface mould, which will not stop damp and mould reappearing.