Our homes are filled with toxic gases and pollutants from all of the synthetic materials we fill them with. Fortunately indoor plants can help soak up these toxins – and NASA has tested the best species to do so.
Indoor Toxins and Pollutants
The harmful gases polluting our indoor environments are called VOCs (Volatile Organic Compounds).
VOCs are a category of chemicals which evaporate at room temperature and constantly off-gas from the synthetic products our homes are filled with.
Hundreds of VOC’s are found in the typical home – the most common VOCs include chemicals like Formaldehyde, Benzene, Trichloroethylene – of which are known irritants and potential carcinogens. Whats more the hundreds of VOCs in our homes may be reacting with each other and having further unknown effects on health.
These dangerous VOC chemicals are often found in the glues and adhesives holding our furniture together, in paints, plastics, cleaning products and deodorisers – and especially in fire retardants sprayed on synthetic carpets, foams and mattresses. More on VOCs in a dedicated article here.
There’s no question VOCs exist and the fact that our homes have become sealed boxes to increase energy efficiency is worrisome as reduced natural ventilation increases indoor VOC concentrations.
Living in sealed off energy efficient buildings with more synthetic products than ever before has made filling your home with natural products and maintaining good ventilation more important than ever. These steps can go a long way in reducing VOC toxins – but with that said removing VOCs completely is unrealistic. That’s where plants come in – natures natural air purifiers.
NASA Research – The NASA Clean Air Study
The question of how to best filter toxins and pollutants from indoor air has long been a priority for NASA.
Living in sealed enclosures like the international space station for months at a time means astronauts are constantly exposed to the VOC’s off-gassing from all the synthetic materials surrounding them.
Of course the problem specific to space is that you can’t just open a window to let in the fresh air – which is why NASA commissioned the Clean Air Study.
The Clean Air Study tested a wide range of plant species to determine which are best at filtering toxins and pollutants from the air.
“…Results indicate that plants can play a major role in removal of organic chemicals from indoor air”
– Interior Landscape Plants for Indoor Air Pollution Abatement: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930073077.pdf
Their findings indicate that not all plant species are good natural air purifiers – with some species much better at filtering VOCs than others. The study produced a list of the best and worst performing plant species to scrub toxins and pollutants from indoor air and follow up reports and a book written by the same scientists expanded on the initial study. Here are the results;
The Best House Plants For Purifying Indoor Air According to NASA
1. Peace Lily – Best
Nasa found that the Peace Lilly filters high levels of benzene, formaldehyde, trichloroethylene, xylene, toluene and ammonia from the surrounding air.
Peace Lilies are popular indoor plants which are easy to grow and care for. In nature they’re found on the floor of tropical forests so try to replicate that kind of environment. Indirect light and a moist well drained soil is best. They don’t like direct sunlight and perform well at room temperature.
Keep this plant out of reach from curious children and pets. The Peace Lilies leaves and flower contains calcium oxalate which is poisonous and can irritate the stomach and respiratory system if ingested in large amounts.
2. Florist’s Chrysanthemum – Best
The Florist’s Chrysanthemum is also a top performer capable of removing high levels of benzene, formaldehyde, trichloroethylene, xylene, toluene and ammonia from indoor air.
They produce colourful flowers as an added bonus and thrive in places with lots of natural light. They prefer cooler temperatures and moist soils.
The leaves are toxic if ingested so put it in a place out of reach of pets and children.
3. Gerbera Jamesonii – Good
The Gerbera Jamesonii – also known as the Barberton Daisy is a noteworthy species worth considering. It has been shown to filter out formaldehyde trichloroethylene and xylene from indoor air.
This plant requires direct sunlight so put in a bright and sunny spot and water regularly.
The Barberton Daisy is also not poisonous so its completely safe to have around pets and children.
4. Hedera Helix – Good
The Hendra Helix otherwise known as English Ivy was shown to be another good choice helping to remove formaldehyde trichloroethylene, xylene and benzene from indoor air.
It’s a hardy plant that prefers a lot of natural light and tolerates cooler to average temperatures.
Keep in mind the leaves are toxic if ingested so keep this one away from children and pets.
5. Sansevieria Laurentii – Good
Sansevieria Laurentii – commonly known as Mother-In-Laws Tongue absorbs significant amounts of VOCs including formaldehyde, chloroform, benzene, xylene, and trichloroethylene.
This is the hardiest plant on this list, surviving in virtually all conditions. It can go without water for weeks and needs very little natural light – giving it a little top up of sunshine every once in a while is all this plant needs to thrive.
How Many House Plants Do You Need To Purify Indoor Air?
So you’ve got a list of good houseplants to effectively absorb a lot of VOCs and purify your indoor air, but how many do you need to make a difference to indoor air quality?
The NASA study sheds some light on this, highlighting that just one plant per 100 square feet of floor area is sufficient to make a substantial difference to indoor air quality. This is of course should be taken as an approximate figure dependant on plant size and room size. As you would expect, the bigger the plant the more toxins it can soak up.
Just one or two of the above species in each room will greatly improve indoor air quality and reduce the amount of toxic VOCs your exposed to on a daily basis.
You can go even further by eliminating the most toxic off-gasing materials in your home and replacing them with safe all natural and non-synthetic alternatives.
Read the next article Reducing VOCs For a Safe & Non Toxic Home to identify the most polluting products in your home and discover their natural alternatives.
Interior Landscape Plants for Indoor Air Pollution Abatement: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930073077.pdf
Plants Clean Air and Water for Indoor Environments: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080003913.pdf
Indoor Air in Typical Australian Dwellings: http://www.environment.gov.au/system/files/resources/87d5dedd-62c2-479c-a001-a667eae21f7c/files/indoor-air-project-dwellings.pdf
Wolverton, B. C., et al. (1984). Foliage plants for removing indoor air pollutants from energy-efficient homes. Economic Botany 38(2), 224-28.
Wolverton, B. C. (1996) How to Grow Fresh Air. New York: Penguin Books.