Houseplants fit purify di air for your home?

Most pipo no realise just how many pollutants dey fly around indoors, wia dem typically spend most of dia time.

For example, many of di products we dey use for cleaning and freshening our homes, schools and workplaces dey add invisible toxins to di air.

"Di smell of fresh no be smell," tok Anne Hicks, a paediatric pulmonary specialist for di University of Alberta.

"If you fit smell am, chemical dey inside di air wey dey enta your nose. So all of dat na air pollution, whether e smell good or bad," she tok.

"Indoor air pollution dey huge, and na relatively unknown frontier, because even my next-door neighbour house get different air pollution fingerprint dan my house go have," Dr Hicks tok.

Indoor air pollution dey highly complex, little regulated, and often beyond individual control. For instance, road traffic dey produce nitrogen dioxide, while moisture and structural issues for buildings fit lead to mould.

Air purifiers with high efficiency particulate air (HEPA) filters fit help. But di initial cost plus di energy to run dem fit dey out of reach for some households.

Dis na one reason wey make am so appealing to think of potted plants as passively, and inexpensively, cleaning di air. Essentially, plant leaves take in carbon dioxide and oda pollutants, wey dem dey come use for various plant processes or broken down.

Especially important hia na di community of micro-organisms and di growing medium (such as soil or compost), wey for many studies dey do more to absorb pollutants dan di plant itself.

One influential NASA study from 1989 find say indoor plants fit remove formaldehyde and oda volatile organic compounds (VOCs) from di air. But di study dey unrealistic for real-world conditions.

In essence, an indoor forestgo dey required to meaningfully reduce VOCs for a home.

"You need plenti plants in very well-lit space to make any measurable impact on di removal of VOCs and many oda gases," tok Tijana Blanusa, di principal horticultural scientist for di Royal Horticultural Society, as well as one researcher for di University of Reading.

Similarly, for carbon dioxide, "you need very large numbers of plants to actually get measurable effects for room scale."

So scaling-up na di answer?

Some researchers, wey include Tijana Blanusa, don move on from individual potted plants to active (living) green walls, wey fit concentrate more plants and also filter air more efficiently due to di way air fit move through dem.

She explain say with active green walls: "Air from di room dey dey pushed or encouraged through di root systems over and above di level wey for happen naturally if to say you let plants siddon inside a pot."

However, such green walls dey expensive to install and maintain.

So pipo continue to experiment with plants.

When building consultancy Cundall move into dia current London office for 2015, dem fill one of di meeting rooms, known as di Green Lab, with plants.

Di aim na to monitor and record di plants' impact on indoor air quality. But e no easy to look after dem all.

E also become clear say di plants no dey get di same effect on air quality as di mechanical ventilation and air purification systems.

Di room now get few large plants for di corners, as well as a small rectangle of preserved reindeer moss on di wall. Di spongy moss dey lovely to touch and look at, but e no get ability to absorb pollutants.

When clients ask about plants for improving air quality, Kavita Kumari, wey be di associate director of Cundall London office, advise dem on plants' advantages and limitations.

She recommend plants wey dey relatively low-maintenance while being able to reduce some VOCs and produce oxygen, though she acknowledge say dis effects dey modest.

One such plant na di snake plant (a common houseplant wey dey sometimes known by di sexist moniker mother-in-law's tongue, due to im sharp shape).

Ms Kumari tok say while most plants dey take in carbon dioxide and release oxygen during di day, dis plant fit do so at night as well.

She say dat simply opening a window to allow di outflow of indoor air pollutants no dey work in highly built-up areas, where outdoor pollutants fit enter at di same time.

Scientists dey work on a new generation of plants wey dem bioengineer to make dem especially efficient at purifying air.

Researchers for di University of Washington don genetically modify pothos plants with a synthetic version of a "green liver" protein wey dem find in rabbits, wey fit process chloroform and benzene.

Di company Neoplants don also tweak genes in pothos plants to enable dem to essentially recycle certain VOCs. As well, di company don produce beneficial bacteria wey dey especially effective at breaking down VOCs, wey dem dey deliver to di plants' root systems. Na dis microbiome rather dan di plant itself wey dey produce most of di plants' air-cleaning effects.

However, even improving on di NASA results 30-fold, as Neoplants dey claim to do, no fit make am feasible to rely on plants alone to clean di air.

So for now, di actual air-purification benefits of indoor plants dey limited. Dem no fit compete with air purifiers.

But plants get oda clear benefits - for instance on mood, creativity and productivity.

Ms Kumari advise clients on complying with di targets set out by di WELL Building Standard, a certification for buildings wey dey promote health and wellbeing. One of dis target na to have 1% of di indoor surface covered by plants.

Dis target falls under di "Mind" category rather dan "Air", wey dey suggest say evidence of di benefits of indoor plants dey stronger for di mental health benefits dan di air quality ones. As Ms Kumari put am, "plants dey give you a sense of calm."

Ultimately, air-quality expert remain in favour of indoor plants. But make we no expect di world of our friends inside pot.