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9 Apr 2020

Air purifying plants: do they really exist?

There are many reasons to love houseplants - but to what extent can they improve your indoor air quality?

Google 'houseplants for indoor air pollution' and you'll find many home decor websites, online shops and cute Pinterest and Instagram accounts touting the benefits of houseplants for purifying your air.

Now that we're required to stay at home, other than for very specific reasons, you might well think your lungs are getting some respite from the pollution you normally encounter on your commute.

But air pollution inside can be three times worse than outside, according to a study commissioned last year for environment charity Global Action Plan.

Do houseplants offer a natural, cheap, easily accessible and attractive way to clean the air?

Read on to find out, plus discover other, simple ways to freshen up the air in your home.

One way to remove some of the polluting particles from the air in your home is to invest in an air purifier. Use our air purifier reviews to make sure you buy one that works well.

Stylish indoor plants

Houseplants, interior-design staples of the 1970s, are enjoying a comeback - particularly among urban millennials who don't have a garden.

If you fall into that category, it's likely you'll have seen plenty of plant-themed posts and adverts popping up on your social media.

Driving this growth in popularity is a desire to reconnect with nature, and to nurture a living thing - buy a plant from online plant service Patch, for example, and it will even have a human name, such as Susie the snake plant, or Sharon the parlour palm. There's also a popular belief that plants can help with general wellness - including detoxifying the air in your home.

African violet, aloe vera, Boston fern, English ivy, heart leaf philodendron, money plant, parlour palm, peace lily, snake plant (also known, a bit rudely, as mother-in-law's tongue) and succulents are among those frequently featured in articles rounding up the 'best air purifying plants for the home'.

These articles will often cite - usually rather loosely - a 1989 study by NASA of indoor plants in space-station environments.

These were the first studies to highlight plants' capacity for air purification, but this research is now being refined.

Do houseplants purify the air?

In certain circumstances, to a limited degree.

We spoke to Dr Tijana Blanusa, principal horticultural scientist at the Royal Horticultural Society (RHS), who explained that research into the impact of houseplants on indoor air quality has intensified over the past few years - particularly the ability of plants to remove carbon dioxide (CO2) and other other volatile organic compounds (VOCs), such as those emitted from paints and furnishings.

When CO2builds up, it results in drowsiness, dizziness and headaches, and creates an impression of a stuffy, closed house.

All leafy green plants will remove someCO2 during the daytime, which they use for photosynthesis.

VOCs can cause eye, nose and throat irritation, nausea and loss of coordination. They can also exacerbate asthma symptoms, attack your nervous system and potentially lead to cancer.

The scale of the studies performed in recent years has ranged from testing individual plants in a room to testing rooms filled with plants.

Dr Blanusa told us: 'So far, the results suggest that the impact of plants on levels of indoor CO2and other VOCs is relatively low, and either more light than you'll typically get at home or in an office, or much greater numbers of plants, would be required to make a significant difference'.

Many factors, including growing media (the potting soil that the plants are grown in), temperature and light intensity, all impact how quickly and efficiently plants can remove VOCs.

And air exchange - or air changes per hour, the number of times air is replaced in a room every hour - will be different in a real-life setting compared with a sealed lab chamber.

Nevertheless, it's an area of ongoing, and exciting, research.

Dr Blanusa says: 'Our research into the removal of other gaseous pollutants is showing promise. And there is mounting evidence that plants in an office can have a positive impact on wellbeing.

'Studies have shown significant self-reported improvements on attention spans, creativity and productivity among office workers'.

Should you buy a houseplant to boost your indoor air quality?

Every little helps when it comes to air quality. Houseplants can be one tool in your armoury when you're combatting air pollution - and they generally make your home a more pleasant place to be.

You'd need vast numbers of plants (and they'd need to be the right plants, maintained under optimum conditions) to make a discernible difference to your indoor air quality.

So there's no need to go ordering plants for the sake of your air quality if you didn't otherwise want them.

And you might end up paying much more than you would have done at a garden centre pre-lockdown, once you've factored in any delivery costs or met a minimum required spend.

Crucially, you should temper your expectations. Don't assume that you're breathing cleaner air just because you've got a few Instagrammable plants.

Houseplants for overall wellness

Air quality aside, houseplants can enhance our lives in a number of ways.

According to the RHS, studies have shown that houseplants can offer the following psychological benefits:

  • improved mood
  • reduced stress
  • increased productivity (adding plants to office environments in particular)
  • increased speed of reaction in a computer task
  • improved attention span (in some scientific studies, but not all)
  • increased pain tolerance.

They can also offer physical health benefits including:

  • reduced blood pressure
  • reduced fatigue and headaches by 20-25% in one study
  • decreased post-operative pain reported by patients in hospital rooms with plants.

Looking out of your window at parks, gardens and wild spaces can be good for your frame of mind, too.

If the view from your window is drab and urban, then getting some houseplants - seeing as you can't get out and about into nature yourself any time soon - could help with your general wellbeing.

Best houseplants

If you do want to buy some plants to cheer up your home during the lockdown, do your research before placing your order. Many plants make poor houseplants.

Consider the light, temperature and humidity conditions in your house or flat. Each plant has its own physiology and preferred growing conditions.

Be prepared to move your plants around your home throughout the year if need be.

Plants recommended by the RHS as being attractive, inexpensive, low maintenance and generally well suited to typical household environmental conditions include bamboo palm, Chinese evergreen (aka silver queen), dragon plant, English ivy, India rubber tree or rubber plant, jade tree, peace lily, spider plant and snake plant.

Coronavirus lockdown: ways to improve your indoor air quality at home

Here are some more effective ways to reduce air pollution in your home during lockdown.

Open a window

In the past, we've advised you to be strategic about when you do this, and avoid times when there's likely to be lots of traffic outside. But data from the London Air Quality Network, run by King's College London, shows that levels of outdoor air pollution, particularly nitrogen dioxide (NO2),have dropped recently as a result of lower traffic.

If there's a bad smell in your house, open a window (and track down the source) rather than spraying air freshener.

Avoid scented products

Cut down on your use of scented products, such as perfumes, and easily inhaled sprays, such as hairspray. Toying with the idea of trying out some eco-friendly toiletries? You're currently staying at home, so if you can find what you need online, now's the perfect time to experiment.

Prevent humidity building up

Maybe you previously showered at the gym, drank your morning tea or coffee at work, and ate out often of an evening. It's especially important to keep humidity levels under control now that all our humidity-causing activities are being done at home.

Open a window and switch on your kitchen hood and fans during and after cooking. Do the same with your bathroom window and extractor fan after showering. Keep an eye out for signs of damp and mould, and buy a moisture absorber or dehumidifier if needed: use our dehumidifier reviews to find a good one.

Air purifiers: can they help?

Another option is to buy an air purifier, although there are limits to what they can do.

Air purifiers can't clear the air of large, heavy allergens that have settled quickly on furniture and carpets. They can only remove allergens that are floating in the air.

Air purifiers that only have a mechanical filter can't capture odours or gases. Those that have an activated carbon filter are claimed to do so, but these claims can't currently be tested.

It's also important to note that air purifiers haven't been scientifically proven to tackle coronavirus, in case you've read anything online suggesting that they can, and were thinking of buying one for that purpose. To stay safe, follow NHS guidance. You can also check out the latest story we published on coronavirus and air purifiers.

Still, an air purifier can reduce the level of pollution in your home - as long as you buy a good one. An air purifier may be particularly helpful if you suffer from hay fever and want to reduce your exposure to pollen, or you have a respiratory condition and find that high levels of pollutants triggers your symptoms.

Which? air purifier reviews

We test with dust, pollen and smoke particles, representing a range of particle sizes.

An air purifier needs to earn 75% in our tests to be a Which? Best Buy. We've reviewed 33 air purifiers and can tell you:

  • how effectively each machine removes allergens from the air
  • how noisy it is on full and low power
  • whether it uses energy efficiently
  • whether the filters are easy to take out, clean and put back in
  • how easy the smart app is to use, if it comes with one.

Head to our list of Best Buy air purifiers to see our recommendations. Or check out our free guide to get more ideas for improving your indoor air quality at home.