I had a university botany lecturer warn our class of the dangers of having too many plants in our college rooms back in the 90s. At that time, our understanding of the impact of plants on air quality was limited by the technology available and the motivations of society. It was a more simple study in the oxygen-carbon dioxide ratio of plants and the relationship between photosynthesis (oxygen production) and respiration (oxygen consumption) by plants. Most people remember that plants produce oxygen in light, what they forget is that plants use oxygen all day and night – hence the warning from my lecturer. At night, we were warned, plants can use all of the oxygen up!
The rate of oxygen use by plants depends on many factors, and he was referring to the small size of our college rooms and the tendency university students have of keeping everything closed up. In a normal house, with normal air exchange, your plants are unlikely to use so much oxygen that they become a risk.
Since then, the world has changed and we have made our homes and offices so energy efficient that ‘normal air exchange’ does not occur – this has resulted in a phenomenon called ‘sick building syndrome’. The solution to ‘sick building syndrome’, believe it or not, is plants!
Our changes in production technology, glues and manufacturing have also contributed to air pollution in our homes. Combine the off-gassing from our manufactured goods, our natural human emissions and our more energy efficient homes and, we are exposing ourselves to a plethora of volatile organic compounds (VOCs) all day and night.
B.C.Wolverton (book pictured) is, in my opinion, the expert when it comes to studies of plants impacting the indoor environment. Wolverton was involved in the initial studies on how plants clean the air and, with improvements in technology, has continued the research to provide updated information. This particular book gives a user-friendly guide to common indoor plants and the benefits that they provide. I highly recommend it!
So, the simple answer to the question “do indoor plants really clean the air?” is yes, but, as with all things in science, the more specific the question, the more detailed the answer. Different plants have different benefits. We are not looking at whether plants produce oxygen or not – that is largely irrelevant to air purification. What we want to know is:
- Are plants removing VOCs?
- What VOCs are being removed?
- What VOCs are removed by which plant?
- How many plants will it take to change the air quality?
- What is the air flow like in my space?
- What items are producings VOCs in my home or office?
There are many other aspects to also consider: the health of the indoor plant itself is important; the potting medium in which the plant is found; the ability of the household to care for the plant; the internal environment and microclimate of the space – all aspects that will impact the ability of a plant to purify the air.
All factors considered, it is better to have indoor plants than not having them. Yes, they do clean and purify the air, but they also create green spaces that help with mental wellbeing. Plants are great decor items and grouping them together creates a lovely vignette.
If you are new to indoor plants, start with a Peace Lily or Devil’s Ivy – both are very easy care plants that cope with over-watering (a common problem for indoor plants) quite well. They will help create a nicer internal environment and start your indoor plant journey on a successful foundation.
The collection and accumulation of indoor plants is addictive – consider yourself warned!