Asthma and housing

Asthma is one of the most common chronic respiratory conditions in the UK, and it is also the condition where the housing-health link is most clearly evidenced. Damp, mould, cold indoor temperatures, poor ventilation, and elevated indoor PM2.5 are all independently associated with worse asthma control. Awaab's Law, introduced in 2024, made it a statutory duty for social landlords to act on damp and mould reports within fixed timescales. Yet for the majority of patients seen in primary care, the housing arm of the intervention is either invisible or arrives only after years of inhaler escalation.

This page is written for clinicians, social prescribers, and household members who want a structured pathway: when does asthma stop being a pharmacology problem and start being a housing problem? And how do you make the referral?

Pediatric versus adult asthma — the housing signal

Pediatric asthma has a tighter relationship with housing exposure than adult asthma. A child spends roughly 90% of their time indoors, with most of that in their home. Bedroom-level exposures — overnight humidity, mould spore counts, dust mite allergens, secondhand cooking aerosols — accumulate over years rather than hours.

The clinical signals that housing is the primary driver, rather than purely allergic or viral:

• Symptoms cluster in autumn-winter rather than spring-summer (cold and damp profile, not pollen)
• Symptoms improve markedly when the child stays elsewhere — grandparent's house, hospital admission, holiday
• Visible mould in the bedroom, persistent condensation on bedroom windows, or surface temperature differential greater than 3°C between bedroom wall and exterior wall
• Inhaler usage stepping up the BTS/SIGN ladder despite good adherence and technique

For adult asthma, the housing signal is often masked by occupational exposure or smoking history, but the same logic applies: if symptoms track the heating season, the building envelope is part of the differential.

What the evidence says — damp, mould, and PM2.5

The Marmot Review and subsequent housing-health literature have consistently shown that cold, damp homes are associated with respiratory morbidity in children and excess winter deaths in adults. The 2024 Awaab's Law debate pulled this into statutory focus: the death of Awaab Ishak from prolonged mould exposure was not a freak event, it was the predictable end-state of a tenancy where damp had been reported and ignored.

For indoor air quality, the key threshold to anchor on is PM2.5. WHO indoor guidance has tightened, and a well-ventilated home with mechanical ventilation (MVHR or continuous extract) typically holds bedroom PM2.5 below 10 μg/m³ over a 24-hour mean. A poorly ventilated home with gas cooking, candles, or biomass can run at 30-60 μg/m³ for hours after a cooking event.

Inhaler step-up versus environmental remediation

The BTS/SIGN and NICE asthma guidelines walk patients up a pharmacology ladder: SABA, ICS, ICS-LABA, add-on therapies, biologics. Each step has a cost, a side-effect profile, and an adherence burden. None of them address the bedroom that is sitting at 14°C and 80% relative humidity overnight.

The decision point is whether the next step on the ladder is genuinely clinically warranted, or whether the patient is being asked to compensate pharmacologically for a building they cannot fix. For housing-driven cases, environmental remediation is often the highest-leverage intervention available — and it is usually cheaper than a year of biologics.

This is where retrofit becomes a clinical intervention. Insulation, ventilation, heating system upgrade, and damp remediation are not cosmetic — they directly modify the exposures that drive symptoms.

When to refer to a retrofit assessor

A clinically-driven referral threshold for retrofit assessment:

• Stepping up the ladder (e.g. moving from ICS to ICS-LABA, or adding LTRA) AND visible damp/mould reported by patient
• Two or more rescue courses of oral corticosteroids in 12 months AND winter symptom dominance
• Any pediatric admission for asthma where the home environment has not been formally assessed
• Patient self-reports cold home or condensation, regardless of disease severity
• Tenant in social housing with documented mould complaint that has not been actioned (Awaab's Law referral)

The referral is to a PAS 2035 assessor, who will produce a whole-house retrofit plan rather than a single-measure quote. This matters because doing one thing badly (e.g. external wall insulation without ventilation upgrade) can make indoor air quality worse, not better.

Social prescribing template letter

A working template for a GP, asthma nurse, or social prescriber to send to the retrofit assessor network:

Dear Retrofit Coordinator,

I am referring [patient name] for a PAS 2035 whole-house retrofit assessment. The patient has [diagnosis: e.g. moderate persistent asthma] which has shown a winter-dominant pattern and a documented response to cold and damp environmental triggers. The patient resides at [address] and has reported [visible mould / persistent condensation / cold rooms].

I would value an assessment focused on: thermal envelope, ventilation strategy, and any damp/mould remediation required. The patient has been informed that this is an environmental intervention, not a pharmacological one, and consents to the assessment.

Please contact me with any clinical questions. Yours sincerely, [clinician].

The assessor will look at fabric, ventilation, heating, and any acute damp issues, then produce a costed plan. Where the household is grant-eligible, the funding routes (ECO4, GBIS, local authority Home Upgrade Grant variants) will be flagged.

Retrofit specification considerations for asthma

For asthma patients specifically, the retrofit specification needs to balance airtightness with ventilation. An over-tightened envelope without adequate ventilation can make indoor air quality worse, not better — trapping cooking emissions, household dust, and CO2 build-up that worsens symptoms.

The technically correct answer for most asthma cases is mechanical ventilation with heat recovery (MVHR). MVHR continuously extracts stale air from kitchens and bathrooms while supplying tempered fresh air to bedrooms and living rooms, with a heat exchanger recovering 85-95% of the warmth. The result is a home that is reliably warm, dry, and well-ventilated — exactly the conditions that asthma management needs.

Key specification points to flag with the retrofit assessor:

• MVHR with bedroom supply diffusers (not just communal air supply)
• Filtration to F7 or G4+F7 to reduce particulate ingress from outdoor sources
• Continuous extract from kitchen and bathroom rather than intermittent fans
• Damp remediation prior to insulation works, not concurrent — the diagnosis of damp source matters
• Heating system that maintains 18-21°C reliably, with bedroom thermostatic control

The assessor should also identify any cold bridges in the existing fabric, because surface temperature differentials are where condensation and mould reliably reappear after retrofit.

Asthma sits at the intersection of medicine and housing. The clinicians who recognise this earliest are the ones whose patients escape the inhaler escalation cycle.