You know that feeling when you see a new leaf unfurl on your favourite plant. It’s that rush of pure, silly joy that makes you all warm and gooey inside.
We know that plants make us happy. But can they affect us physically?
A cumulative body of evidence from over two decades of research says ‘yes’.
A study by the Agricultural University of Norway, one of the foremost studies exploring the health benefits of plants, found that plants have a significant effect on decreasing incidences of head colds and influenza.
The study analysed office workers from various businesses, splitting them into two groups. Employees of the first group were given plants on a windowsill, on their desk and a large floor plant each. The other group worked in standard office conditions with no plants.
The researchers compared the two groups by analysing their responses to questions about their health. Here’s what they found…
- Neuropsychological symptoms (fatigue, headache, concentration problems) were reduced by 23% when plants were present. Fatigue reduced the most – by 30%
- Mucous membrane symptoms (cough, sore throat, stuffy nose, eye irritation) were reduced by 24% overall when plants were present. Cough decreased by 37% and dry throat by 25%
- Dry or flushed skin was reduced by 23% with plants in the workspace.
The researchers suggested that health improvements were due to two factors: improved air quality and the psychological value of being in a more pleasing environment.
1. Plants purify the air.
The famous NASA Clean Air Study was conducted to find a way to purify the air inside space stations. The researchers placed 12 different plant species in sealed chambers. Plants included Ficus species, Peace lily, Snake Plant, Bamboo Palm, Golden Pothos and others. NASA tested three types of Volatile Organic Compounds (formaldehyde, benzene, and trichloroethylene) by adding them to the chambers and recording how much of the gas was left after 24 hours.
NASA reported that across all of the trials, up to 70 % of the added VOCs and bioeffulents (yucky things that humans exhale, like carbon dioxide and viruses) were removed, with the top performing plant being the Bamboo Palm. NASA's Dr. Wolverton recommended one plant per 100 square feet (9.3 m2) of space.
However, critics have recently argued that urban buildings aren’t perfectly closed systems like those in space, and therefore a whole jungle of plants would be needed to have a noticeable effect. It could be kind of cool to work in an indoor forest, if you’re ok with caterpillars dangling from your laptop and having to weave between palm fronds on your way to brainstorms...but maybe not that practical.
Side note: How do plants absorb toxins?
Through photosynthesis they absorb gases as they breathe through tiny pores on their leaves. The gases travel down to the roots where microorganisms in the soil & roots break down the nasties turning them into plant food.
Naysayers suggest that a regular air exchange filter could do a better job. Well, whether that’s true or not, why not have both? Even if it’s just the presence of plants that makes us feel like we’re breathing in cleaner air, it’s half the battle won. Also, NASA only tested three VOCs, which undeniably proved plants’ ability to remove toxins. What about all the other gunk in the atmosphere that hasn’t been measured? Who knows what wonders plants are performing right under our noses!
Dr. Meattle’s story
Doctors told Kamal Meattle, Indian environmental activist and CEO of Paharpur Business Centre & Software Technology Incubator Park, that Delhi’s pollution was killing him, after his lung capacity dropped to 70%. So, he greened his entire building with 1200 plants for 300 people. Now that’s only four plants per person, and he recorded remarkable improvements to worker health and productivity.
Then there’s Vybarr’s story, an asthmatic in London, who after adding indoor plants to his home, has reduced his medication intake to a quarter of what he used to need.
Sweat it baby!
2. Plants raise humidity
Over and above purifying the air, plants sweat – yeah they’re like a really sweaty species without having to do a squat. This happens through a process called transpiration where the roots suck up water, which then evaporates through the leaves. In fact, most plants lose 90% or more of their water through transpiration (a fully grown tree in the sun can easily lose several hundred litres of water in a single day from transpiration).
Studies show that this accounts for about 10% of the moisture in the atmosphere! Just think how humid jungles are, or that moist pine-cone aroma of an alpine forest.
Ok, but what’s so special about reveling in plant sweat?
Humidity makes it harder for germs to travel
That’s one of the reasons flu spreads in winter. Winters are dry. Lab experiments, for instance, have looked at the way flu spreads among guinea pigs. When the air is moister, the epidemic struggles to build momentum. But in dry air it spreads like wildfire. And comparing 30 years’ worth of climate records with health records, Jeffrey Shaman at Columbia University found that flu epidemics almost always followed a drop in air humidity.
Every time we cough or sneeze a mist of particles is expelled into the air. In moist air, these particles may remain relatively large, dropping to the floor. But in dry air, they’re shown to break up into smaller pieces – enabling them to stay aloft for hours or days.
Plants with large, broad leaves (like many rainforest plants) provide a greater humidifying effect than those with needle-shaped or small, rounded leaves. In winter, group houseplants together to raise humidity levels and place them near a humidifier if necessary. Browning leaf edges could indicate a lack of humidity. Try aim for levels around 50 – 60%.
3. Plants boost healing
Bringing flowers or a plant when visiting someone in hospital is not just a cliché. It’s been proven to help surgery patients recover faster. One study recommends them as a “non-invasive, inexpensive, and effective complementary medicine for surgical patients.” Plants as medicine!
The study, conducted at Kansas State University, found that viewing plants during recovery from surgery led to a significant improvement in physiologic responses as evidenced by lower systolic blood pressure, and lower ratings of pain, anxiety, and fatigue as compared to patients without plants in their rooms.
Plants have undeniable benefits. It’s a kind of leafy magic that goes beyond the ability of science to measure or explain. We feel it instinctively. It stems from a primal urge to belong to nature. Our inner self recognises it’s good for survival.
I used to get sick a lot. I’m prone to coughs, dry irritated throats and flu, and would get sick at least three times during the year, often with bronchitis and laryngitis. Then, I quit my corporate office job and studied landscape design four years ago. Since working with plants, including having two big ones and eight small to medium plants in the 40m2 office (which is strictly not air-conditioned), I’ve had flu once in the last four years! Nothing else in my diet or lifestyle has changed. And even if it's psychological, it's worked for me, either way.
Opinion piece by Carolyn Ashmore, founder of The Atrium, botanical emporium and online plant shop.