We spend 90% of our lives indoors, in both private and public spaces: the office, the gym, the supermarket, the pub, the cinema, home. There’s a growing understanding that the quality of the air we breathe indoors has a noticeable effect on our physical wellness, both in terms of day-to-day comfort and long-term heart and lung health.

Although spring and summer are traditionally the most miserable outdoor periods for dust allergy and hay fever sufferers and asthmatics, those same people – those with respiratory sensitivities – are likely to have symptoms indoors throughout the year. Indoor air quality is at its worst in winter, when we shut ourselves inside and seal the windows.

In fact, depending on where you live, exposure to indoor pollution may be more harmful than outdoor. The most likely to be affected are children, elderly people and those with cardiovascular disease or respiratory problems. 

While we don’t have much control over the air in public spaces, what we can improve is the air quality in our homes. Following are some practical steps you can take and some examples of technology that can make a difference.

What's in the air in your home?

There are some common air pollutants that could affect your health. As well as heightened levels of carbon dioxide, there will be particulate matter and VOCs. 

Particulate matter

This is also known as particle pollution, PM or aerosol. Basically, it's all the little bits floating about in the air that you might breathe in. It’s a mixture made up of solid particles and drops of liquid – dirt, dust, pollen, soot, smoke, chemicals and metals.

The concerning particles are the very small ones: those under 10 micrometres across. (For reference, a human hair is approximately 75 micrometres thick, so 10 micrometres is very tiny indeed.) Larger particles are usually filtered out in the nose and throat but particles of this size can make their way into your lungs and affect your heart, your respiratory system and your immune system. 

VOCs

VOC stands for volatile organic compound. VOCs are gases, often emitted by products when they’re used. Some examples of well known VOCs are benzene and formaldehyde, which are carcinogens, and toluene, which is toxic.

VOCs can come from a range of sources but the ones in your home are likely to be from cleaners or disinfectants, air fresheners, cosmetics and deodorants, dry-cleaned clothing, a wood burning stove or fire, paint, varnish, adhesives or sealants.

Monitor your air quality

A good first step is to find out about your current indoor air quality. 

Buy an air quality monitor

There are a number of options on the market. A rough guide to cost is £150-£300, depending on what functions they offer. Towards the top end, you'll get a smart air monitoring device which you can interact with via a free, downloadable app.

A monitor of this kind will give you information on VOCs in your air, particulate matter, carbon dioxide, humidity, temperature and pressure.

Previously, we reviewed the Awair 2nd edition, which we rated 4 out of 5 stars. More recently, we reviewed the Wave Plus, from Airthings. Although the device has some limitations – a key one being that it does not measure particulate matter – it is a high-quality monitor. You can buy the Awair and the Airthings Wave Plus from retailers including Amazon in the UK.

The Wave Plus also monitors radon, the radioactive gas naturally created by the decay of small amounts of uranium in soil and rocks. Every area has some radon, but it's recommended that you test for the gas if you live in an area that is more likely to be highly affected. If you're in the UK, you can use this map from Public Health England to find out whether your area is high or low risk.  

Buy a carbon monoxide detector

Every year, 60 people in England and Wales die from accidental carbon monoxide poisoning. If you have a poorly installed or maintained appliance like a cooker, a heater or a central heating boiler, or if an appliance is damaged or malfunctions, you may be at risk of poisoning from this odourless, colourless gas.

The best way to protect yourself is with a carbon monoxide detector. Fortunately, these are inexpensive and effective. You can buy one from £10-£20. Every household should have at least one of these, depending on the size of your home. If you’re living in rented accommodation and didn't purchase your own appliances, you should buy one right now.

Clean your air

Once you have a good sense of your air quality, you can take steps to improve it. If you've already bought an air quality monitor, you may be able to start seeing evidence of your efforts.

Clean the filters in your appliances

Most of your existing appliances have filters to trap dust and lint. Once they get gummed up, not only are they less effective in their function, risking your appliance heating up or malfunctioning, but they'll also be less effective in pulling more dust out of your air.

Start with your vacuum cleaner. Empty the bag if it has one, and clean the filter. Newer vacuum cleaners may have dust bins that can be removed completely and cleaned. Next, check the filter in your clothes dryer, your air purifier, any heaters, fans or air conditioners. While you're at it, you could clean the fans on your PC.  

We've saved the worst but most important job for last: cleaning your extractor fan. (If you didn't know they needed to be cleaned or that the filters – in most cases – can be removed, then you are in for a special time of it.)

Your kitchen is the source of many of the air pollutants at home and you’ll be surprised at how much cooking affects the air quality of your home.

In 2017, a team from the University of Colorado Boulder led by environmental engineer Marina Vance built a test house on a university campus to measure the effects of cooking and cleaning on indoor air quality.

They discovered that even toasting a piece of bread pushed air quality to unsafe levels. Cooking a roast dinner created a spike in particulate matter that could rival the outdoor air quality of Delhi, which is among the most polluted cities in the world.

I used the Airthings Wave Plus to measure the air quality in my kitchen. As you can see, in the following screenshots from the app, both the TVOC and CO2 content in the air spiked after cooking a Sunday roast. (The device does not monitor particulate matter.) This was while using both a hood extractor and a larger, kitchen extractor fan. It shows why you need to keep your fans clean and use them whenever you cook.  

Airthings monitor images

Vacuum your soft furnishings with a HEPA-grade filter cleaner

Fabrics, carpets, sofas, pillows and mattresses can become repositories of pet hair, dust and dander. Although curtains are the only one of the above items that you can guarantee you’re not going to collapse onto face-first, the advice to severe dust allergy sufferers is to replace your curtains with blinds. At the very least, take them down and put them in the washing machine.

So how much more important is a clean mattress? And when did you last vacuum that?

People who are very sensitive to dust can buy anti-dust mite mattress covers, like this one from Tural, which is on sale from Amazon for £21.95. If you don’t think you need to cover your entire mattress, you can just buy pillow cases. Amazon has a four-pack of hypoallergenic pillow protectors which guard against mildew, dust mites and more for £8.99.     

For everyone else, a deep-clean of all of your soft furnishings should make a big difference to your home air quality. Your bed is where you spend the most time, so start there. Strip your bed and vacuum your mattress and pillows.

Move on to your sitting room and vacuum the cushions on your sofa and chairs. And that brings us to our next piece of advice.

Your cleaning process will be much more effective if you have a vacuum cleaner with a HEPA filter.

HEPA (high efficiency particulate air) filters must trap 99.97% of particulates that are 3 micrometres or larger. Not only is that a really high level of dust removal, and one that’ll get the dust mites out of your mattress, but a HEPA filter will retain the dust it gathers and prevent it from being blown back into the air of your home.

Bear in mind, however, that if you choose a bagless vacuum cleaner, you’ll be releasing some of the dirt and dust you just captured back into your living space. Ideally, if you're using a bagless cleaner you should empty it into an outside bin. However, many handheld cleaners have a limited dust capacity and need to be emptied frequently. If you also live in a flat, it's not realistic to take it outside every time.

If you are, or live with, a dust allergy sufferer, bagged vacuum cleaners are the better option. They make a big difference in trapping dust and keeping it locked away once it’s collected.

Investing in a robot vacuum cleaner with a HEPA filter is a great way to keep the air quality in your home at a high standard. In fact, any robot vacuum cleaner is a good option for people with respiratory problems, as it can be set to run while you're out. By the time you're home, any remaining dust has literally settled. Here's our round-up of the best robot vacuum cleaners we've reviewed.  

The Samsung Powerstick Jet has a HEPA filter and we rated it 4.5 stars out of 5. You can buy it here. It’s bagless, however, and pretty pricey.

A more budget-friendly bagged option is the Halo Capsule, which we also reviewed and really liked.

Invest in an air purifier

An air purifier will pull air through a filter and then circulate the cleaned air back out into your living space. It’s not the cheapest option, as not only should you run the purifier for the majority of the time but you also need to replace the filters regularly for it to be effective.

 If you buy a 50-watt air purifier and use it for 10 hours a day, every day, on a standard tariff, it will cost you about £31 per year to run.

We liked the Dyson Pure Hot + Cool a lot. It’s an air purifier, heater and a fan in one. Our reservation is obviously the price. £549 is a lot to spend on even an aesthetically pleasing, well-engineered air purifier. There’s a somewhat more affordable option in the Dyson Pure Cool Me, which is now available for £299.

Start good air habits

The final stage in keeping the air in your home clean is to be more aware of air quality and to change your habits to protect it.  

Always use the extractor fan

We discussed the reasons you should do this above but the bottom line is: the extractor fan is there for a reason. Switch it on, not only when you're cooking but also when you're using cleaning products.  

Cleaning: don't combine products and don't use a spray

Cleaning products that are safe on their own can become dangerous when combined. Most people know that if you mix bleach and ammonia (for example, bleach and toilet cleaner), you can create chloramine gas, which is toxic. But did you know that bleach and vinegar is another combination to avoid? Blend the two and you’ll get poisonous chlorine gas.

Even products that are safe to use can have a negative effect if you breathe them in. This is why it's recommended to avoid cleaning sprays. Long-term use of spray cleaners is associated with an increased incidence of new-onset asthma and other respiratory problems.

If you use bleach-based products, use liquids that can be poured straight onto the area you want to clean. Breathing in bleach regularly, or over an extended period of time, is particularly associated with lung disease. 

Don’t OD on scented stuff

Plug-in air fresheners and scented candles – especially those made from paraffin – release chemicals into the air as they heat up.  

And it’s not just the ingredients that go into them that are the problem. For example, limonene, which is used to create citrus scents, can produce formaldehyde when burned.

Are there enough of these pollutants to cause you actual harm? The answer is that there’s not enough evidence to say. The British Lung Foundation says that candles, when used occasionally, “are unlikely to prove much of a health risk”, but the general advice is not to burn them every day and only in well-ventilated rooms. Incense should be used even more sparingly, as there is strong evidence that links its use to lung disease.  

Avoid wood-burning stoves and open fires

Is there anything better than an open fire on a winter’s day? In air quality terms, the answer is: almost anything. Wood smoke is full of the particulate matter that is directly linked to cancer, strokes, heart attacks and other things you don’t want to be thinking about right now.

More people are turning to open fires and wood-burning stoves, not only for reasons of comfort and aesthetics but from the mistaken idea that they are a wholesome and sustainable form of heating.

But that’s not true. A UK Government study found that domestic wood burning causes almost two and a half times more pollution than traffic. It’s not hard to extrapolate from this what effect your cosy fire is having on the air quality in your home.

Open a window

People are much more aware of outdoor pollution and its dangerous effects, than of the air quality indoors. So much so that they feel safer when hermetically sealed in their homes. But the best advice, when cooking, cleaning or if food is burned, is to let a little air in from outside.