How to improve your indoor air quality at home
The air we breathe can have a significant impact on our health. Find out how you might be unwittingly generating air pollution in your home, and what you can do to improve indoor air quality.
We all know that outdoor pollution is a problem. But the chances are you don't worry too much about the quality of the air in your own home.
Yet many of the things we do to make our homes more comfortable, such as decorating, burning candles and using air fresheners, can increase our personal exposure to pollutants, and contribute significantly to our collective national emissions.
And, as many of us are spending most of our time indoors at the moment, this isn't something we should ignore.
If you're elderly or you have a pre-existing health condition, such as asthma, heart disease or chronic obstructive pulmonary disease (COPD), you're particularly vulnerable to the effects of pollution.
Children and young adults are also more at risk, because they have faster breathing rates and their lungs are still developing.
Open your windows
Opening your windows regularly is the easiest way to remove polluting particles from the air in your living space.
It's especially important to do this in winter, when humidity is high, however tempting it is to keep all windows tightly closed.
Be strategic about when you do this. If you live near a busy road, keep the windows closed at peak traffic time. If you suffer from hay fever, don't open your windows in the morning, when the pollen count is highest.
Use your cooker hood and extractor fan
Cooking produces grease, smoke, smells and moisture. Switch on your kitchen hood and fans during and after cooking – even if you find them annoyingly noisy – to clear the air of oil and other ingredients that have evaporated into it. This will also limit damage to your walls and kitchen cabinets.
If you can, get an extracting cooker hood, sometimes called a vented hood or ducted hood, rather than a recirculating one. Extracting hoods send the air out of your home through the wall or roof, while recirculating models filter the air through a carbon filter and recirculate it inside your kitchen. If you have a recirculating hood, make sure you clean and change the filter regularly.
An extractor fan can be installed in any room where you want to control humidity, gas or smoke. An extractor fan in your bathroom can pull moist air out of the room, preventing mould spores growing. It can also remove the after-effects of using toiletries and cleaning products.
Don’t use unvented (aka vent-free) appliances such as freestanding gas and paraffin heaters. These may sound convenient, as they don't require a vent pipe or chimney, making them easy to install, but they release a number of harmful pollutants into your room.
All gas heaters, even when burning properly, produce carbon dioxide (CO2). When carbon dioxide builds up, it results in drowsiness, dizziness and headaches, creating an impression of a stuffy, closed house.
Avoid blocking or decorating over existing permanent ventilation features, such as air bricks and trickle vents on windows, even if you've heard that doing so could help you save on your heating bill. They are there to allow air to circulate naturally when windows and doors are closed. They also allow oxygen in, moderate internal temperatures, reduce the risk of condensation, and prevent pollutants building up inside.
In 2017, we carried out an investigation into indoor air pollution in three houses: one from the Victorian era, one from the 1950s and one new-build. We performed a range of everyday tasks in the houses – vacuuming, cleaning, using air fresheners and candles, cooking a fry-up and burning toast – and measured the air quality in each of the houses before and afterwards. We found that the highest levels of air pollution were in the 1950s house, where well-intentioned home improvements such as cavity wall and roof insulation, double glazing and other energy-efficiency measures had made the house overly airtight.
Vacuum frequently – particularly if you have pets
Make sure you vacuum often to remove polluting particles.
The best vacuum cleaners will pick up twice as much dust as the worst, and they’re much better at stopping particles from leaking back out into your room.
It's particularly important to vacuum if you have pets, as pet dander can add to the air pollution in your home. Dogs and cats naturally shed old hair – some twice yearly, some all the time.
Pollen can also attach itself to your pet's fur and be carried indoors, which isn't ideal if you're a hay fever sufferer, so keep your pet off your soft furniture and bed if you can.
When pet hair is trodden into carpets or rugs it can be hard to get out, as it tangles in the carpet fibres. It's much easier to keep hard floors clean than it is carpets.
Make sure you vacuum regularly, using a vacuum cleaner that's great at whisking away pet hair.
Consider the following when choosing a vacuum cleaner:
- Cylinder or upright – Cylinder models are useful for stairs and hard-to-reach places, but many struggle with pet hair. Uprights cover large areas of floor more easily, but the brush bar in the floor head can get tangled easily.
- Cordless or corded – A cordless vacuum might make quick clear-ups easier, especially if you opt for one that converts into a handheld vac.
- Bagged or bagless – Bagged vacuum cleaners can protect you from contact with pet dander, but you’ll have the ongoing cost of replacement bags.
- Extra tools – Some come with extra nozzles and tools, which can be good for pet hair. Mini turbo tools with a rotating brush bar can help by picking up fluff in places where you can’t use the main floor head, such as sofas or stairs.
We run our vacuum cleaners through a specific pet-hair test. Some, including ones that are great in other respects, really struggle with pet hair, leaving you going over the same spot again and again.
Equally, some that are specially designed for pet hair are less effective than all-round models.
We also test how well each vacuum cleaner retains the particles it sucks up.
Be on the lookout for damp and mould
High humidity levels can cause respiratory problems, and provide a perfect breeding ground for mould spores, dust mites, clothes moths, fleas, cockroaches and other nasties.
If you've got asthma or a weakened immune system, you should take particular care to keep humidity levels in your home in check. According to charity Asthma UK, 42% of asthmatics surveyed said that mould and fungi triggered their asthma.
Avoid hanging wet washing indoors. You might not have any other option if you don’t have a tumble dryer or an outdoor clothes line, but when moisture in the air meets cold surfaces, such as windows and walls, it condenses.
If you must dry your washing indoors, open a window so water vapour can escape, or use a dehumidifier and close the windows and doors of that room (otherwise you're making the dehumidifier work even harder).
Use a clothes airer rather than hanging your washing directly on the radiator, which can cause condensation. It can also add to your heating bills, damage the delicate fibres in your clothes, and complicate your case if you're renting and trying to get your landlord to do something about your damp problem. It can even be a fire hazard.
Set your clothes horse up in the sunniest spot in your home, unless that’s your bedroom.
Don’t put damp clothes back in your wardrobe. Getting mould out of a wardrobe can be a nightmare, as you can’t just set to it with bleach and a stiff-bristled brush because this could damage the materials.
Ventilate when cleaning and decorating
When painting, decorating and cleaning, make sure that the room is well ventilated. Chemicals found in everyday products, such as paints, aerosols and cleaning products with limonene and pinene (familiar lemon and pine smells), can emit volatile organic compounds (VOCs).
After decorating, wait for paint and solvent smells to subside before using the room again.
Reduce your use of scented candles, easily inhaled sprays, aerosols and furniture polish (dust with a damp cloth or electrostatically charged duster instead).
If there's an unpleasant odour in your house, track down the source rather than using an air freshener.
Exposure to very high levels of VOCs can cause eye, nose and throat irritation, headaches and nausea. In the long term, they can also cause damage to the liver, kidneys and central nervous system.
Some VOCs are more dangerous than others – for example, terpenes, including limonene and pinene, are considered lower risk than benzene (from petrol and cigarette smoke and, potentially, from paints and solvents), which is considered high risk. Nevertheless, some VOCs (especially terpenes) can combine with ozone from outside air to form gases, including formaldehyde. This is a lung irritant that can cause allergic reactions and, at very high levels, be carcinogenic.
New flat-pack furniture, lino and carpet, fabrics, bedding, glues and insulation can also release formaldehyde.
NICE (the National Institute for Health and Care Excellence) says that women who are pregnant, and babies under 12 months, at are increased risk from exposure to indoor air quality. NICE says that pregnant women, new mothers and people who live with them 'should reduce their use of household sprays, air fresheners and other aerosols and always follow product instructions', 'avoid activities that produce particulate matter such as using candles' and 'always keep the room well ventilated during these activities'.
Use natural cleaning products
Consider switching to ways of cleaning that are less polluting.
- E-cloths are microfibre cloths designed to remove more than 99% of bacteria. All you need to do is rinse the cloth and wring it out, draw it across your dirty surfaces and wash it afterwards with hot water or in the washing machine.
- White vinegar is great for worktops, hobs, floors and windows.
- Baking soda works wonders for stains and smells, it's non-abrasive and it saves you having to scrub or use bleach. You can use it to wipe away old food residues from the inside of a fridge, for example, or you can add it to pots and pans to help lift stubborn, crusty foods.
Be aware of the risks of wood-burning stoves
Asthma UK and the British Lung Foundation recommend avoiding the use of wood-burning stoves.
A 2020 study by researchers at the University of Sheffield and the University of Nottingham found that residential stoves released high intensities of PM2.5 and PM1 – particulate matter already identified by the World Health Organisation (WHO) as a very serious health risk, able to penetrate your lungs and enter your blood stream. Researchers installed air quality monitors in the homes of people with log burners and measured the level of harmful particulate matter over a four week period.
If you already have a wood-burning stove or fire, you should burn only untreated, fully dried wood. Some types of fuel, such as wet logs and house coal, produce far more particulate matter than dry logs and low-sulphur smokeless fuels, such as anthracite coal.
When wood doesn't have a good enough supply of oxygen, it creates more smoke and potentially harmful emissions. It also increases sooty build-up in your chimney. Make sure the flue damper is open before you use it. Clean the flue and chimney often so that smoke has a means to escape.
Keep the fire constant, so that the flue stays at the right temperature. This will help to avoid carbon monoxide (CO) coming down the chimney.
Install a carbon monoxide alarm
CO is odourless and can be deadly. But even non-fatal levels can be harmful, particularly for those with impaired or weak lungs. Ensure you have a working CO detector, and that it's positioned correctly.
Don't smoke indoors
You don't need us to tell you about the dangers of smoking. You might be surprised to learn, though, that when you smoke, more smoke gets released into the air – where others can breathe it in – than goes into your lungs.
The NHS says that second-hand smoke (the smoke you exhale, plus the sidestream of smoke from your cigarette end) puts your family at risk from the same diseases as smokers, such as lung cancer and heart disease. Children living in a smoky house also have a greater chance of developing asthma, breathing problems and other allergies.
Smoke can linger in the air for hours after you've finished smoking, and it can spread from room to room. Opening a window or door won't banish the smoke, as it can blow back inside and stick to surfaces such as soft furnishings, to be released later, sometimes in more harmful forms (third-hand smoking).
The London Fire Brigade warns that smoking indoors is also a major cause of fire fatalities.
If you're going to smoke, go outside, close the door behind you, and move away from the house.
Remember that you're still bringing smoke particles back in with you via your clothes, though.
Reduce dust in your home
However hard and often you clean, you'll never get your house free of dust, but you can reduce it. Don't wear shoes indoors, wash bedding regularly and take non-washable items outside to shake clean.
NICE also says that you should avoid buying a second-hand mattress if you're allergic to dustmites.
Consider an air purifier
Buying an air purifier shouldn't be the first or only thing you do to reduce your indoor air pollution: first, deal with the problem at its source by minimising any pollution you're creating, then get into the habit of ventilating often.
But, as well as taking the above steps, you could consider an air purifier. An air purifier could be particularly useful if you have allergies or respiratory problems, live near a major road or industrial facility, or you're often exposed to second-hand smoke or odours that you have no control over.
Air purifiers aren't perfect: they don't offer a solution to the problem of air pollution, but they can reduce the level of pollution you're breathing in.
Choose one with a HEPA filter if you want to remove particles such as dust, pet dander and smoke particles from the air. Filters with names such as 'HEPA-type' aren't held to the same standards of filtration efficiency.
If you need to remove smells or gaseous pollutants, you'll need one with an activated carbon filter. A HEPA filter won't filter out these smells, as they only remove particles.
We test each air purifier with dust particles, cigarette-smoke particles and pollen, so we can tell you which do the best job of removing these pollutants.
Air pollution in a rented property
If you're renting, you're going to have less control over the indoor air quality in your home than if you owned your own place.
Contact your landlord if:
- there's inadequate ventilation (for example if trickle vents, extractor fans or cooker hoods are damaged)
- repairs are needed to stop water entering the building
- heating and insulation improvements are needed to prevent condensation.
If your landlord is uncooperative, and refuses to take these actions, contact your local council. In March 2019, a new law came into force to make sure rented houses and flats are 'fit for human habitation', ie safe from things that could cause you serious harm. Depending on your tenancy agreement, if the property you're renting falls short of this, you can take your landlord to court (the Homes Act).
Even if your tenancy agreement means you don't have recourse to the Homes Act, you should still contact your local council if you're worried about conditions in your home, and it can take action on your behalf.