You may have heard of the “sick building syndrome” where the actual building we live and work in is making us sick. There are a mass of chemicals that are hidden in the paint we use, the cushions and chairs we sit on, the clothes we wear, the carpets we walk on… it can cause everything from coughs, allergies, skin problems, dry eyes, right down to cancers and inflammatory diseases of the respiratory tract.
At home we can do what we can to reduce our exposure to these aggravating chemicals, we change our paint, we remove some plastics and man-made materials, we replace our cleaning products with natural alternatives, we put in plants, open the windows, we use lightbulbs that give off less gas, we swap plastic tables for untreated wood ones...
While sceptics might have previously laughed at their office manager bringing in plants, now, due to the lobbying of workplace consultants, interior designers, and facility managers, who actually want the best for the organisation, they are embracing it. It always baffled me why a CEO might think that their manager might be encouraging something that would not benefit their staff, for surely, happy staff, means staff retention, productivity, creativity and what does that mean? Cost savings, quicker solutions to problems, increased confidence, less staff sick days, and so on. What does all that mean? Money. It means more money. Surely that should make any CEO, CFO or SME boss very happy?
My background is academia (if you didn’t know I’m a PhD nerd, turned media head), I like to look at evidence and then make my own mind up too. Don’t we all? So, this is the first in a series of literature reviews, exploring the case for Biophilic Design, I’m aiming for one every week or so to help inspire people during and post Lockdown. It’s not an extensive analysis, I’ll revisit each theme as the weeks unfold, so you could think of each of these as little academic spring boards to fire off your own research or start a debate with your colleagues and friends next time you’re allowed to meet with them!
So, here goes…
The case for plants and air
Way back in the 1980s a NASA study showed that plants would help people living in a confined space for long periods of time and also the adverse is true that it is not possible to survive without contact with nature. [1]
It concludes which plants clean the air more than others, for instance English Ivy, Peace Lily, Parlour and Lady Palm, chrysanthemum morifolium. There are others, but these are like the super heroes of the plant world, they seem to the best at removing various volatile organics and other chemicals such as:
Formaldehyde (used in plywood, glues, tobacco smoke, even some shampoos and shower gels, nail polishes…) , https://www.cancer.org/cancer/cancer-causes/formaldehyde.html
Trichloroethylene (used to process cotton, wool, dry cleaning, certain adhesives, paint strippers, pesticides, etc) https://www.atsdr.cdc.gov/phs/phs.asp?id=171&tid=30 now classified as a “human carcinogen”.
Benzene (used in solvents, motor fuels, automobile exhaust, paints, adhesives, cigarette smoke) https://www.who.int/ipcs/features/benzene.pdf https://pubchem.ncbi.nlm.nih.gov/compound/Benzene#section=Food-Additives-and-Ingredients cause of cancer, anaemia – is classified by the World Health Organisation that Benzene is a major public health concern.
Ammonia (used in fertiliser, cleaning products, used to make synthetic fibres and plastics; it is naturally occurring, but we suffer increased exposure from household products such as window cleaners, etc). https://www.atsdr.cdc.gov/phs/phs.asp?id=9&tid=2 (not carcinogenic, but can cause lung disease, blindness in extreme situations).
Xylene (occurs naturally as one would assume from its Greek root, “xyl- meaning wood, but is now used in nail polish, inks, rubber, leather, adhesives) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2996004/
Toluene - (also used in permanent markers like xylene, paint thinners, glues) https://medlineplus.gov/ency/article/002829.htm can cause nausea, tiredness, confusion.
This is not arguing the case that these chemicals cause health issues, it is to show that we can help ease the “threats” to our health by implementing biophilic design using plants.
Further research published by the original researcher on the NASA project goes on to show that some of the microorganisms living in the soils of these houseplants, remove benzene from the air for instance. [2]
The first study quoted above resulted in a suggested solution to fix air pollution. As a result of their study they saw how “leaves, roots, soil, and associated microorganisms of plants” can “reduce indoor air pollutants”. They also saw how combining an air filter design with plant systems they could remove “high concentrations of indoor air pollutants such as cigarette smoke, organic solvents, and possibly radon… Plant roots and their associated microorganisms then destroy the pathogenic viruses, bacteria, and the organic chemicals, eventually converting all of these air pollutants into new plant tissue.”
Or maybe not
Recently, it has been argued that this study might not be as definitive as we think, as it was conducted in an experimental environment, and not a real-world scenario. [3]
But I’m questioning this recent (late 2019) analysis, because the debunking research is modelled, not real-world either, so it should also be taken in the manner it was presented. [4] The authors have not conducted the experiments, they have mathematically modelled the impact. I respect that fact that the original research was conducted in restricted environments, 1-metre squared spaces where the air cannot escape, where in reality you do get some movement in homes and office spaces. Sometimes not a lot but you do get it. The authors of this recent paper, however, do agree that plants do clean the air. What Cummings and Waring’s suggest is that we need more plants per square metre to do a complete air exchange. Short of taking our desks outside and living in a jungle to replicate that volume, bringing in plants to help with air quality will make an impact. The authors do urge that further study should be made. Indeed, further research has been done, some by NASA themselves. [5]
What is worth noting, however, is Michael S Waring, the co-author of this questioning paper (it’s always good to question), [6] is producing some interesting research on pollutants in the home as well, including measuring the risk of bringing in chemicals on the soles of our shoes. I first read about pollutants in the home in the 80s and was struck by the volume of chemicals and toxins we bring in with us, not just on our shoes (which I’ve nearly always left by the door, just think doggy poo if you need putting off wanting to bring the outside in that way…) but also in the plastic packaging, the acrylic jumpers, all the artificial materials around us. It made sense to my analytical brain that surely the more natural we can get the better. The further we are away from where we started, as the hunter gatherers we still are to a greater degree, surely would have a detrimental effect on us as human beings. Same goes for the food we eat, the E numbers, the preservatives, the GSM… but that’s another story.
Air
Waring wrote another article with Patrick Gurian [7] where the latter states: “There is strong evidence for a link between ventilation rate and occupant welfare and productivity. It is well-known in the indoor air field that higher instances of airborne disease infection in commercial buildings are associated directly with low ventilation rates. Increasing ventilation rates above minimum standards has been shown to reduce symptoms of ‘sick building syndrome’ and absenteeism in offices.”
We should all recognise that there is quite a bit of air movement in any interior space, there is natural air circulation and air from outside does creep in. It’s the speed and volume of that air shift which is what challenges most workplaces and homes. If you’re fascinated enough to want to measure what it’s like at home and if you’re into micro- or milligrammes per cubic metre I suggest you purchase a passive sampler and knock yourself out in your bedroom or workplace. If you are blessed with a large room with a large window or door to work in, good for you, keep that door or window open for as long as you can before hypothermia kicks in. If like most of us, you work in a small room or cubicle, then doing what we can to reduce that afternoon fatigue because the air quality is proven to have dipped to below acceptable levels is a good thing. When there is an increase in CO2 (carbon dioxide) our energy drops, our mood swings, we get headaches, our productivity falls. It’s not rocket science to understand that increased CO2 will increase if you are in a closed environment, every time we breathe out, we emit CO2, multiply that with say 10 other people in a space and you’ve got some fun breath work! [8]
Opening the window in your home or workplace is ideal of course, and if you live in an older building you’re likely blessed with more air movement. Having proper ventilation is of course essential (although you wonder which oxygen-deprived planet some office managers originate from, going by the suffocating air of some offices I’ve worked in in London over the last couple of decades).
The Harvard Business Review commented that “researchers found that every time you double the rate of outdoor air delivered into an office, worker performance improves by 1.7% across four simulated office tasks: text typing, addition, proofreading, and creative thinking. It’s no surprise, then, that an analysis of sick leave data for more than 3,000 workers across 40 buildings found that 57% of all sick leave was attributable to poor ventilation.” They also note, which will prick up the ears for many Finance Directors: “The benefits of higher ventilation alone are estimated to be between $6,500 and $7,500 per person per year.” [9]
Back to plants
So how many plants do we need around us? For environmental psychologists, it could just be one because the busyness of the leaves, is too great a visual stimulus, for others just one can increase the air quality by 25 per cent. If you’re confused, there is a new app out “Plant Life Balance” (which if I was more commercially minded, I would have set up an affiliate link to earn some revenue, but I’m not, and I haven’t). The app is based on research from the University of Melbourne and RMIT who analysed 100 peer-reviewed research papers from the past half century to help work out how many plants we need to reduce the toxic organic compounds in our indoor environments. I probably should write something on the case for trees, we all know they are the lungs of our planet. Why should it be any different in our homes? Irrespective of whether the gorgeous imagery in the app does it for you or not, it is interesting that the research was carried out as part of the Clean Air and Urban Landscapes Hub collaboration. They concluded that you need 1 medium-sized plant per 2.2 square metres, they suggest that they can reduce up to 90% of airborne chemicals (depending on what the pollutant is and the type of plant). A nice big leaved plant is good, as is clearing your home and workspace of as many yucky and unnecessary plastics and toxins as you can. [10]
We do also know that “seeing” greenery, plants and nature around us improves our wellbeing. This is another aspect of Biophilic Design. Views of nature and plants really do have a positive impact on our mindset.
There are many studies, which you might already be well versed in, and many of the thought leaders, interior designers, academics, environmental psychologists I’ve interviewed here on our Journal of Biophilic Design podcast and published articles also cite research and experience as to why plants as good for us psychologically, emotionally and have far-reaching health benefits.
One of the main sources is Kaplan [11] who states that having plants around you has been shown to:
“Lower blood pressure (systolic)
Improve reaction times
Increase attentiveness
Improve attendance (at work and school)
Raise productivity (at work)
Improve well-being
Improve perceptions of the space
Lower levels of anxiety during recovery from surgery
Raise job satisfaction”
In the Journal of Physiological Anthropology published an article by Lee, et al., suggests that “active interaction with indoor plants can reduce physiological and psychological stress compared with mental work. This is accomplished through suppression of sympathetic nervous system activity and diastolic blood pressure and promotion of comfortable, soothed, and natural feelings.” [12]
There is also the case that caring for something (the plant on your desk) also engenders kindness and compassion and care for others, including human beings as well as your partner’s pot plant. I’ve mentioned it before in a podcast, but one of the best side-effects that biophilic design can have is an increased awareness of a love of the natural world on our fragile planet, and hopefully we might take care of it, just as we might take care of the little Peace Lily bouncing away on our desk.
Dr Vanessa Champion, Editor, Journal of Biophilic Design
Next up, The Sound of our Space (subscribe if you’re wired in a way that wants to question the why, the how, and the what, do email me if you have comments on this, would love to hear from you).
[1] ( “A study of interior landscape plants for indoor air pollution abatement: An Interim Report” was published in 1989 BC Wolverton; WL Douglas; K Bounds (September 1989). Interior landscape plants for indoor air pollution abatement (Report). NASA-TM-101766)).
[2] Wolverton, B. C. and J. D. Wolverton. (1993). Plants and soil microorganisms: removal of formaldehyde, xylene, and ammonia from the indoor environment. Journal of the Mississippi Academy of Sciences 38(2), 11-15.) and Wolverton, B. C. (1996) How to Grow Fresh Air. New York: Penguin Books.
[3] Potted plants do not improve indoor air quality: a review and analysis of reported VOC removal efficiencies (https://www.nature.com/articles/s41370-019-0175-9 Bryan E. Cummings & Michael S. Waring Journal of Exposure Science & Environmental Epidemiology volume 30, pages253–261(2020)).
[4] https://scholar.google.com/citations?user=M0hJrFcAAAAJ&hl=en
[5] https://ntrs.nasa.gov/citations/20080003913 (Plants Clean Air and Water for Indoor Environments 2007) https://ntrs.nasa.gov/citations/20190002850 (Plants for Life Support in Space 2019) https://ntrs.nasa.gov/search?q=how%20plants%20clean%20the%20air%3F
[6] https://drexel.edu/now/experts/Overview/waring-michael/
[7] https://drexel.edu/now/archive/2015/December/IAQ-perception/
[8] https://www.nature.com/articles/s41893-019-0323-1 Direct human health risks of increased atmospheric carbon dioxide, Tyler A. Jacobson, et al., Nature Sustainability volume 2, pages691–701(2019)]. See also https://www.theguardian.com/environment/2019/jul/08/indoor-carbon-dioxide-levels-could-be-a-health-hazard-scientists-warn https://www.nature.com/articles/s41893-019-0323-1 Review article: Direct human health risks of increased atompheric carbon dioxide, Jacobson, etc al, in Nature Sustainability vol 2, Aug 2019, 691-701 (where they also cite a great deal of previous research on CO2 impact on us). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3548274/ Environ Health Perspect. 2012 Dec; 120(12): 1671–1677. Is CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2Concentrations on Human Decision-Making Performance)
[9] https://hbr.org/2020/04/what-makes-an-office-building-healthy?ab=hero-main-text
[10] https://pursuit.unimelb.edu.au/articles/how-a-pot-plant-or-five-is-good-for-you
[11] https://www.psychologytoday.com/gb/blog/urban-mindfulness/200903/plants-make-you-feel-better
[12] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4419447/ J Physiol Anthropol. 2015; 34(1): 21. 2015 “Interaction with indoor plants may reduce psychological and physiological stress by suppressing autonomic nervous system activity in young adults: a randomized crossover study”
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