麻豆社

Most of us know that air pollution caused by traffic is bad for our health. But the reality is that indoor air pollution can be just as bad – both at work and in our own homes. It’s been linked to a range of health problems, like asthma, wheezing, conjunctivitis and eczema.

Studies show that plants really can improve our wellbeing, leading to a boost in mood, memory and productivity.

The most concerning air pollutants that researchers have looked at are volatile organic compounds, or VOCs, which can be found in fire retardants, aerosol sprays and cleaning products. One such compound is limonene, which we might know by its delicious citrus scent. Unfortunately, it reacts with the ozone in the air to form the potentially dangerous chemical formaldehyde!

Another chemical where high levels can cause problems is carbon dioxide, resulting in poor concentration and decision making. Ventilating areas well can help with both these things, but where that’s not possible, houseplants are a surprisingly good and natural way to purify the air.

A green solution?

The suggestion that house plants could help with air quality came from an unlikely source. In 1989, the space agency NASA showed that houseplants could significantly lower levels of VOCs and CO2 in the air in a sealed chamber. What was lacking, was the proof they could work in our own homes or offices. It did encourage a wave of research into plants’ potential to absorb chemicals, and since then, research has taken off looking at their impact in different – more realistic – living environments. One study, for example, suggested that introducing potted plants to 60 offices with high levels of volatile organic compounds reduced levels of these compounds by between 50 and 75%.

One study in Norway assessed the impact of introducing plants to an office or school and the radiology department of a hospital and found that filling the office with houseplants led to fewer coughs, headaches and fatigue.

Less stress and better productivity

In addition to making you feel physically better, there have been claims that having indoor plants can be good for your mind too. If you’re already a plant lover, you may notice yourself feeling more comfortable, breathing in more deeply and feeling the benefits of the calming effect of nature - and there has been research which supports this. Studies show that plants really can improve our wellbeing, leading to a boost in mood, memory and productivity. One even found that when employees were able to view plants from their desk, they performed better in a specific test of concentration by 19%.

How do they help?

Dr Tijana Blanusa from the Royal Horticultural Society has been studying the ways plants improve air quality. She explains that there are several ways plants can work to remove compounds from the air. On the underside of the leaf, there are pores called stomata that let the air in, and water vapour out. A lot of gaseous compounds are removed though this pathway, while at the same time, water vapour causes our air to become more humid. Another way is through the soil, where microorganisms break down the compounds.

In the podcast, Michael Mosley asks Dr Blanusa which type of species give most benefits. “We have found that generally those fast-growing, thirsty, physiologically active plants are giving more service,” she says. “In practical terms, those would be the likes of peace lilies and devil’s ivy.”

Other plants which are lower maintenance might be less beneficial. “The ones which are more succulent are easy to look after, but physiologically, they're doing very little in terms of gas exchange,” Dr Blanusa says. So while they can still make you feel good, liven up your room, and require minimal effort to look after, they are unlikely to be having any impact on indoor air pollution. Studies have shown that it is the plants which need lots of sunlight, photosynthesize more and grow more quickly which have the biggest benefit.

For the greatest effect, it’s good to pack a number of them in, says Dr Blanusa. “For a small room, we're talking probably at least five or six plants to have a measurable impact on CO2 concentration and NO2 concentration.”

Look after them so they look after you!

Dr Blanusa also explains it is important to treat your plants well to give them the best chance of affecting indoor gases and humidity. Plants require light in order to be physiologically active, and this leads to more gas exchange. “The more light we can give them, the better they're going to perform for us,” she says. Make sure you don’t over- or under-water them too!

So if you want to enhance your productivity, concentration and maybe even refresh your indoor air, it might be worth bringing some nature indoors. Remember, if you’re looking for the greatest benefits, keep an eye out on which kind of plant you’re going for, place them in the brightest corner and make sure they get enough light and water. Being nice to them will certainly help.

To find out more, listen to Just One Thing: Get Some Houseplants