How to improve air quality at home - it’s the big health issue nobody’s talking about

We’ve known for decades that air pollution is harmful to our health, but until recently more attention has been paid to the outdoor air we breathe than pollution generated within our homes. And while many of us have gotten into the habit of checking air quality at home, not many people know what they're looking for or how they can change the results.

‘As outdoor air quality improves in our towns and cities, indoor air pollution becomes a greater proportion of the problem of polluted air,' explains Professor Frank Kelly, head of the Environmental Research Group at London’s Imperial College.

'The effects of poor indoor air on health are less well understood compared to outdoor air quality, but there is evidence that poor indoor air quality can have adverse effects on health, such as increased risk of heart disease, stroke and respiratory infections.’ 

A 2020 report by the Royal College of Physicians explains, ‘Air quality changes from building to building, place to place, over time and in response to the activities taking place indoors. The main way people are exposed is by inhaling pollutants, but they can also be ingested or absorbed through the skin.’

Why is good air quality at home important? 

‘It’s important for the simple fact that we spend two thirds of our time in our homes on average,' reminds Nicola Carslaw, Professor in Indoor Air Chemistry at the University of York. 'It is the microenvironment where we spend the most time and so the quality of air that we breathe is important for our overall exposure.’

According to Professor Kelly, the short-term health effects associated with indoor pollutants include respiratory infections from mould, but in the long-term, there’s a multitude of health effects including asthma, allergic rhinitis, coughing and wheezing, cognitive impairment (in the case of carbon dioxide poisoning) and cancers – such as mesothelioma from asbestos and those caused by second-hand tobacco smoke. A YouGov study commissioned by Bluair, The Power of Clean Air, even found that air pollution affects the quality of our sleep. 

Types of indoor air pollution

‘Some of the major sources of indoor air pollution are cooking and cleaning,' explains Professor Carslaw. 'Other sources are burning candles, using woodstoves and air-freshener use. These are mostly chemical sources, but there are also biological sources such as mould.’

There are two types of air pollution: airborne particles and gases. The best air purifiers will remove the former, but not the latter, although models with an activated charcoal filter will remove formaldehyde (such as Dyson’s Hepa Cool).

These are the main culprits and their sources:

• Nitrogen dioxide, carbon monoxide and particulates from gas cooking and heating, open fires and wood burners or burning candles, can cause asthma.
• VOCs (volatile organic compounds) in paints, carpets, laminates, cleaning products and air fresheners can cause asthma.
• Formaldehyde (or HCHO) in scented candles, plywood and particleboard, tobacco smoke, foam insulation, varnishes and wood finishes can cause asthma.
• Environmental Tobacco Smoke (ETS). This includes first, second and third-hand smoke from smoking and vaping. The third kind is released as a vapour from surfaces in the home. This is the source of the persistent odour that smoking or vaping can leave. ETS can cause cancers.
• Microbial aerosols, such as bacteria, fungi and pollen can exist on the surface of dust particles and cause wheezing and allergic rhinitis (cold-like symptoms). They also include airborne viruses such as flu and covid.

• Damp and mould. With modern homes becoming more airtight, mould is becoming more of an issue as water vapour is also retained. Atmospheric water vapour levels are also naturally higher in the UK compared to other parts of the world. The presence of damp and mould increases the risk of asthma, allergic rhinitis, coughing and wheezing.
• Radon. This naturally occurring gas enters buildings from the ground they are built on and can accumulate there. It is the second highest cause of lung cancer after smoking and high levels of exposure can cause childhood leukaemia. Geography and geology both play a part here, so check with the UK Health Security Agency if your home is in a high-risk area. If you’re a property owner, this would have been done as part of your solicitor’s searches when you bought the house. Testing your home’s radon levels is simple and inexpensive using detectors. The UK Radon Association has all the information and advice you might want.

How to improve air quality at home

 Take these simple steps to purify the air you breathe for a healthier future.

1. Open the windows

Keeping the heat in can lead to a build-up of moisture in the air that increases the likelihood of mould, mildew and damp on walls and windows – especially in high-humidity rooms like kitchens and bathrooms. Air rooms regularly and make sure the trickle vents on your window frames are kept open. 

These are slots with a sliding cover that allows you to open and close the vent. Check they are not covered by curtains and blinds and keep internal doors open, to make them as effective as possible.

2. Cook smarter

‘When cooking, use the extractor fan or open a window,' advises Professor Carslaw. 'Use the back rings of the hob rather than the front as the extractor fan works more efficiently with these. Steaming and boiling food is better than frying. And, finally, switch your gas hob to electric or induction when renovating.’

Furthermore, keep the window open for 10 minutes after cooking to allow particles, gases and moisture to disperse, and note that extractor fans should be vented outdoors rather than recirculate air into the kitchen to be fully effective. Of course, if you can use one of the best air fryers then you can avoid the hob much more easily.

In addition, research has shown that different types of cooking oil produce different levels and sizes of particles. To minimise both, switch from olive oil to sunflower oil when frying. 

3. Reconsider that roaring blaze

Everyone loves the cosy crackle of a wood-burner or open fire, but all solid fuel combustion contributes to both indoor and outdoor pollution. It’s important that your stove is well maintained and that you only burn well-seasoned wood to minimise emissions.

4. Swap wax candles for battery-powered ones

Burning candles produces particulate matter and formaldehyde. If you choose scented candles, these release VOCs (volatile organic compounds) in addition. If you just love a scented candle and don’t want to deny yourself the pleasure, set a time limit on usage and open a window. 

5. Don’t use home fragrance

Other forms of home fragrance are also polluting the air in your home with VOCs and other chemicals. Aerosols are the worst, thanks to the propellants in them. Incense produces particulate matter and plug-ins release VOCs.

6. Stop spritzing scented products

Scented cleaning and personal-care products emit VOCs, so look for unscented everything – from shampoo to surface cleaner.

‘Avoid scented products if you live with someone who is prone to respiratory issues,' advises Professor of Indoor Air Chemistry, Nicola Carslaw. 'Switch from spray cleaners to cream cleaners and from spray-on deodorant to roll-on. Ecofriendly cleaners often contain as many fragrance compounds as regular cleaners, so are unlikely to reduce your exposure. Look for unscented products instead.’

7. Dry washing outdoors

In his book Dampness in Buildings, construction expert Alan Oliver concluded that drying clothes indoors can produce 3-7.5 litres of moisture. Drying laundry indoors can also increase levels of other pollutants if scented laundry liquid and fabric conditioner have been used. 

The safest way to dry is outdoors, or if that’s not possible, dry clothes indoors with an efficient dehumidifier running nearby. Yes, there’s a cost attached to this, although it’s significantly cheaper than running a tumble dryer. Our investigation into the cost of running a dehumidifier found that it will set you back from 5-14p per hour.

8. Renovate with safer building materials

Plasterboard for stud walls, particleboards like MDF and plywood, as well as insulation materials, floorings and coatings such as paints, waxes and varnishes all contain pollutants. If you are planning a project, check DEFRA’s Indoor Air Quality Report for a full list of materials to avoid or replace with safer alternatives.

9. Use an air purifier

Many have limited effectiveness at cleaning indoor air and some actually generate secondary pollution. However, the latest generation of the best air purifiers can be efficient at removing pollutant particles – ideal if you have asthma or allergies. 

For example, Bluair’s HepaSilent technology can now remove 99.97% of particles and Dyson has taken a step beyond with its HepaCool models that can detect and destroy formaldehyde. 

Whatever you choose, it’s crucial that you regularly replace the filter for it to work effectively. Shop around, looking for the highest CADR (clean air delivery rate) and check the range of a device, as many will not cope with large spaces and buying more than one could be required.

FAQs