Plants and humans have evolved together in a beautiful symbiotic relationship — albeit one that we are now abusing. Whether we’re using them for food, shelter, medicine, or simply to breathe, without plants we just wouldn’t exist. But do we undervalue just how much we can benefit from plants? In our increasingly urbanised world, where more than half of us live in cities, how important is it to bring nature back into our everyday environments, like at home or in the office? Here are several scientific reasons why you need more plants in your life.
Humans produce energy by turning oxygen and glucose into carbon dioxide and water. Plants produce energy by photosynthesis, combining sunlight, water and CO2 to produce oxygen and sugar. This cycle is one of the basics for life on Earth. The usual concentration of CO2 outside is between 380 and 500 parts per milligram (ppm), but studies show that inside, this can increase to typically around 1000 ppm. This can have a number of effects on health, including lowering mental performance and impairing decision-making.
Increasing the number of indoor plants helps to balance things out, converting excess CO2 into oxygen. However, you should be careful about which plants you choose for which rooms. Without light most plants switch to producing energy through respiration rather than photosynthesis, using oxygen and sugar to make CO2 and water, just like us. Some plants, like sansevieria trifasciata employ a different kind of metabolism developed to conserve water use, which means they actually carry on absorbing CO2 and emitting oxygen throughout the night. Why is this important? Because increased oxygen levels at night have been shown to aid a deeper sleep.
As well as effectively filtering the air of CO2, some plants have been shown to reduce levels of volatile organic compounds (VOCs) present in many indoor environments, like benzene (a component of gasoline) and formaldehyde (used in many industrial resins). The volatile nature of these compounds means they can easily vaporize at room temperature, causing harm over time if persistently inhaled. NASA and the Associated Landscape Contractors of America (ALCA) released a study in 1989 that proved plants can significantly reduce the levels of these compounds in the air. The Boston fern was shown to reduce levels of formaldehyde in a sealed container by 70% over 24 hours, whilst the gerber daisy absorbed 67.7% of benzene. How do plants achieve this kind of filtration? In a recent interview, Dr Bill Wolverton, lead researcher for the NASA Clean Air Study, said:
“Plants have two ways to remove indoor air pollutants. Firstly, plant leaves absorb certain organic chemicals and destroy them by a process called ‘metabolic breakdown.’
Secondly, when plants transpire water vapor from their leaves, they pull air down around their roots. Many microbes live on and around a plant’s root system in an area called the ‘rhizosphere.’ These microbes break down chemicals into elements that both the plant and themselves can use as a source of food and energy.”
Plants have evolved this system for energy creation over years of exposure to naturally occurring VOCs, such as those emitted from rotting plant matter.
Mental health benefits
Plants are often added to office environments in an attempt to make staff less stressed and more productive. Can plants actually do this and is there any scientific evidence? A study conducted by Washington State University placed participants in a windowless computer room and saw their blood pressure and emotions monitored whilst completing a timed computer task. They were monitored twice: once with plants and once without. The participants were more productive, with a 12% quicker reaction time on the computer task. They were also less stressed, with systolic blood pressure lowered as much as four points when plants were present. Participants also reported feeling 10% more attentive with plants present.