The Indoor Air Quality Problem
Most people assume that outdoor air is more polluted than the air inside their homes. But research from environmental health organisations consistently shows that indoor air can contain significantly higher concentrations of certain pollutants — including volatile organic compounds (VOCs), dust mites, mould spores, pet dander, and combustion by-products.
Since most people spend the majority of their time indoors, improving the air quality in your home can have a meaningful impact on respiratory health, sleep quality, and general wellbeing — particularly for children, the elderly, and anyone with asthma or allergies.
Common Indoor Air Pollutants
- VOCs (Volatile Organic Compounds): Emitted by paints, varnishes, cleaning products, new furniture, and synthetic carpets.
- Particulate matter: Fine dust, pollen, pet dander, and smoke particles that remain airborne for hours.
- Biological pollutants: Mould spores, dust mites, and bacteria, often thriving in humid conditions.
- Carbon monoxide: Produced by gas appliances, boilers, and open fires if not properly ventilated.
- Radon: A naturally occurring radioactive gas that seeps up from certain soil and rock types — a concern in some regions.
- Nitrogen dioxide: Produced by gas cookers and unflued gas heaters.
Step 1: Ventilate Regularly and Strategically
Ventilation is the most effective and lowest-cost way to improve indoor air quality. Open windows on opposite sides of your home to create cross-ventilation, even for just 10–15 minutes a day. Ventilate particularly after cooking, cleaning, showering, or using any chemical products. In new or energy-efficient homes, a mechanical ventilation system with heat recovery (MVHR) provides consistent fresh air exchange without losing heat.
Step 2: Control Humidity
Mould and dust mites thrive in humidity above 60%. Keep indoor humidity between 40–55% by:
- Using extractor fans in kitchens and bathrooms
- Running a dehumidifier in basement or damp rooms
- Fixing leaks and damp sources promptly
- Drying laundry outdoors or in a well-ventilated tumble dryer (not on indoor radiators)
An inexpensive hygrometer (humidity monitor) lets you track levels in different rooms.
Step 3: Reduce VOC Sources
Many common household products release VOCs continuously, not just when in use. To reduce VOC exposure:
- Choose low-VOC or zero-VOC paints when redecorating.
- Air out new furniture, mattresses, or rugs in a garage or outdoors before bringing them inside.
- Switch to fragrance-free or naturally scented cleaning products.
- Avoid aerosol sprays where possible — sprays disperse fine droplets deep into the lungs.
- Store chemicals and solvents in a shed or garage, not inside the home.
Step 4: Vacuum and Dust Effectively
Regular, thorough vacuuming removes particulate matter before it becomes airborne again. Use a vacuum with a HEPA filter — these capture particles as small as 0.3 microns, including allergens that would otherwise pass back through cheaper machines. Dust with a damp or electrostatic microfibre cloth rather than a dry duster, which disperses particles into the air.
Wash bedding at 60°C weekly to kill dust mites, and consider allergen-proof mattress and pillow covers if anyone in the household has allergies or asthma.
Step 5: Consider an Air Purifier
A good air purifier with a true HEPA filter and an activated carbon filter can noticeably reduce allergens, VOCs, and odours in a room. They're most beneficial in bedrooms, where you spend many hours breathing. When choosing a model, look for one sized appropriately for the room (check the Clean Air Delivery Rate, or CADR) and consider ongoing filter replacement costs.
Air purifiers complement but don't replace ventilation and source reduction — they're most effective as part of a broader strategy.
Step 6: Be Careful with Combustion Sources
Gas hobs, log burners, and candles all release combustion particles and gases indoors. Always use the extractor fan when cooking with gas. Ensure your boiler and any gas appliances are serviced annually. Fit carbon monoxide detectors near all combustion appliances and on every floor of your home. If you burn wood, use well-seasoned dry wood and ensure the chimney is swept regularly.
Quick-Win Summary
- Open windows for 15 minutes daily
- Run extractor fans when cooking and showering
- Vacuum with a HEPA vacuum weekly
- Wash bedding at 60°C
- Switch to fragrance-free or natural cleaning products
- Install CO detectors
- Monitor humidity and dehumidify if needed
Improving indoor air quality doesn't require expensive equipment or major renovations. Most of the biggest gains come from consistent habits and a few simple changes to how you ventilate and clean your home.