Indoor Air Quality & Lungs (UK Guide)

Why indoor air quality matters

We spend most of our time indoors. Tiny particles (PM_2.5 and smaller), gases like nitrogen dioxide (NO₂) and ozone, moisture, mould spores, and volatile organic compounds (VOCs) can irritate airways, trigger asthma or COPD flare-ups, and increase the risk of chest infections. Ultrafine particles are small enough to reach deep into the lungs and may pass into the bloodstream.

UK homes are often tightly sealed for warmth. Without smart ventilation, everyday activities like cooking, cleaning, showering, and burning fuels can quickly push indoor pollutants and humidity into ranges that bother sensitive lungs.

Breathing red flags — act now

• Severe breathlessness, unable to speak in full sentences, chest pain, blue lips/face, or drowsiness/confusion — call 999.
• Child breathing fast, ribs pulling in, grunting, or lips look blue — call 999.
• Possible carbon monoxide (CO) exposure (headache, dizziness, nausea, collapse, pet illness) — get fresh air, call 999.
• Worsening wheeze/cough despite your inhalers or plan — contact your GP or NHS 111.

Who’s most at risk

• People with asthma, COPD, bronchiectasis, long-term cough, or recent chest infections.
• Babies, children, pregnant people, and adults over 65.
• Anyone with heart disease or weakened immunity.

Common indoor sources that irritate lungs

• Cooking: Frying and grilling release fine particles; gas hobs add NO₂. Self-cleaning oven cycles can off-gas.
• Heating: Open fires, wood/coal stoves and portable unflued heaters release particles and gases.
• Moisture & mould: Condensation, leaks, and cold corners promote mould and dust mites.
• Cleaning & fragrance: Sprays, air fresheners, incense, scented candles, and plug-ins emit VOCs and particles.
• Smoking & vaping indoors: Second-hand smoke and aerosols linger and deposit on surfaces.
• DIY & furnishings: Fresh paint, new furniture, and flooring can off-gas VOCs; sanding creates dust.
• Outdoor air leaking in: Nearby traffic, bonfires, or neighbours’ stoves can raise indoor PM during certain hours.
• Radon (some UK areas): Naturally occurring gas that can enter basements/ground floors; test if you live in a higher-risk area.

Simple home monitoring (safe & legal)

• CO alarm: Install and test weekly in rooms with fuel-burning appliances.
• Humidity & temperature: Aim roughly 40–60% relative humidity to discourage dust mites and mould, and avoid very dry air that irritates airways.
• CO₂ monitor: A helpful proxy for ventilation. Persistent readings well above 1000–1500 ppm during occupancy suggest you need more fresh air.
• Symptoms diary: Note triggers (cooking, sprays, cold mornings), peak-flow (if advised by your GP), and what helps.

Quick wins this week

• Use extractor fans during and 10–20 minutes after cooking/bathing; open a window on the opposite side of the home for short “purge-venting”.
• Cook “cleaner”: lids on pans, back burners under the hood, simmer/air-fry/slow-cook instead of deep-fry when you can.
• Door discipline: Keep kitchen/bathroom doors closed while extracting to control moisture and fumes.
• Damp-dust weekly with a microfibre cloth; vacuum slowly with a HEPA-filter machine.
• Fragrance-free first: Switch aerosols and plug-ins to minimal-fragrance or fragrance-free options.
• Shoes off at the door and use a sturdy doormat to cut outdoor dust coming in.
• Dry laundry smartly: Vent tumble dryers outside; if air-drying indoors, use a dehumidifier nearby.
• Smoke-free home: Get help to stop — see Smoking Cessation.

Ventilation that actually works in UK homes

Short, sharp cross-ventilation (5–10 minutes with two windows on opposite sides) can refresh air without chilling the whole house. Use kitchen and bathroom extractors every time you cook or shower. If you have trickle vents, keep them open in occupied rooms. In colder months, time ventilation around cooking/bathing and when outdoor air is cleanest (often away from rush hour or neighbour burning).

Mechanical ventilation with heat recovery (MVHR) helps in very airtight homes, but needs correct sizing, installation, and filter changes.

Moisture, condensation & mould

• Fix leaks quickly; heat rooms evenly to reduce cold surfaces where moisture condenses.
• After showers, run the fan and keep the bathroom door closed until mirrors clear.
• Target indoor humidity 40–60%. A dehumidifier can help in bedrooms and laundry areas.
• For small patches of mould on non-porous surfaces, wipe with detergent and water; dry thoroughly. For large or recurring areas, especially on porous materials, seek professional help.
• Report persistent damp and mould to your landlord/agent in writing. Keep photos and dates (see If you rent).

Heating & cooking choices

• Avoid indoor combustion where possible: Open fires and solid-fuel stoves add fine particles. If you must use them, use compliant “Ready to Burn” fuels and keep flues maintained — but cleaner options are better for lungs.
• Gas hobs: Always run an effective extractor hood ducted outdoors; open a window for cross-flow. Consider switching to induction when you can.
• Portable heaters: Avoid unflued fossil-fuel heaters; they add moisture and combustion gases.

Air purifiers (what helps, what to avoid)

• HEPA, not ozone: Choose a true HEPA unit (H13/H14) with a clean air delivery rate (CADR) matched to your room. Avoid ozone or “ioniser-only” devices.
• Place & pace: Run on higher settings during cooking/cleaning and when symptoms flare; keep doors slightly open for whole-home circulation or use one per key room.
• Maintain filters: Replace on schedule; clogged filters reduce effectiveness.

Cleaning, fragrances & sprays

• Prefer liquids or pump sprays over aerosols; avoid mixing products.
• Use unscented or low-VOC products where possible. Ventilate during and after use.
• Avoid incense and frequent candle burning; soot and ultrafine particles can irritate lungs.
• New paints/furnishings: ventilate well for several days; consider low-VOC paints.

Smoking & vaping indoors

Second-hand smoke increases risks for children and adults with lung conditions. Vaping aerosols can also irritate airways and leave residues. Keep your home smoke- and vape-free. For support to quit, see Smoking Cessation.

If you rent or live in social housing

Report damp, mould, and faulty ventilation/heating in writing and keep records. If health is affected, your GP or respiratory nurse can document the impact. Your local council’s environmental health team can inspect serious hazards.

Lung symptoms to track

• Wheeze, tight chest, cough, or breathlessness that worsens with cooking, cleaning, cold mornings, or in certain rooms.
• Night-time symptoms, early-morning cough, or needing reliever inhalers more often.
• Frequent chest infections or prolonged recovery.

When to speak to your GP or 111

• Worsening asthma/COPD symptoms or using your reliever more than usual.
• New persistent cough over 3 weeks, coughing up blood, unintentional weight loss, or chest pain — contact your GP.
• Concerns about sleep-related breathing (snoring, pauses, daytime sleepiness) — see Sleep Apnoea (OSA) Awareness.
• For vaccines that reduce chest infection risk, see Vaccinations (Flu, COVID, Shingles, Pneumococcal).
• For staying well in extremes of weather or cold homes, see Hydration, Heatwaves & Cold Homes.

FAQs

Do houseplants clean the air?

They’re good for wellbeing but don’t meaningfully reduce indoor pollutants at home-realistic plant numbers. Ventilation, source control, and HEPA filtration matter more.

Is a dehumidifier or an air purifier better?

They do different jobs. Dehumidifiers reduce moisture (helping mould/dust mites). HEPA purifiers remove particles (helping smoke, cooking fumes, dust, pollen). Many homes benefit from both.

What humidity is “best” for lungs?

Roughly 40–60% relative humidity balances comfort and reduces mould/dust mites; very dry air can irritate airways, very humid air favours mould.

Should I stop using gas hobs immediately?

You don’t need to panic, but always use a good extractor vented outdoors, ventilate well, and avoid high-heat frying. Consider induction when you next upgrade.

Are ozone or ioniser air cleaners safe?

Avoid ozone-generating devices; ozone can irritate lungs. Ionisers without HEPA don’t address most particles and can create by-products.

Glossary

PM_2.5: Fine particles ≤2.5 µm that can reach deep into the lungs.

NO₂: Nitrogen dioxide gas produced by combustion (e.g., gas cooking, heaters, traffic).

VOCs: Volatile organic compounds from paints, cleaners, and fragranced products.

CADR: Clean Air Delivery Rate — how much filtered air a purifier supplies.