How humble houseplants can improve your health
What I want to do for the first half of this talk is to talk about our research. I hope to emphasise how undervalued plants are. I think in the wider community there's a lack of understanding about the function of indoor plants. Everyone knows that they look nice and they're decorations, but they clearly do a lot more than that. Firstly, what I'm going to talk about is the first section of this. I'm going to talk about how plants affect indoor air quality specifically. Plants have got a great deal of ability, not only to affect the air as a whole in urban areas, but also specifically what we're interested in is the indoor air.
Indoor plants can improve pretty much every characteristic of indoor air quality. Okay, so whether it's particular to noise, chemicals or anything like that. Carbon dioxide, they can improve the quality of air markedly. They can also, of course, contribute to the goal of sustainability. I'll come to that later. That's been - it's a roundabout way we've come to discover that. After I've finished with the lab stuff, Meg's going to talk about one of the more recent directions of our research which is in towards human wellbeing.
It appears that plants have got abilities to improve our health beyond just affecting air quality. So Meg's going to talk about how plants can measurably reduce sick leave. Not just philosophically. Plants can measurably produce data that shows people get sick less often, raise productivity, satisfaction. It improves school performance. It's a shame Meg got to talk about that stuff because I like that stuff, and improved mood states. So indoor plants are clearly a lot more than decorations. It's nice that Ambius got on board with that idea quite early.
Firstly, a bit of background why urban indoor air pollution is important. Firstly, Australia as you may know is the most urbanised country in the world. More than any other country people in Australia live in cities. Of those people, most people spend more than 90 per cent of their time indoors. Think about what you did today. Most people spend all their time indoors. So we all like to think about the environment and how the bushland and natural environments and how they improve eco system services and the way we live.
Where we live as people is indoors. Our environment is inside an office or inside a house. That's our environment. That's where we exist. So indoor environmental quality then is really critical to our wellbeing. That's our place in the world, is indoors. So we can't ignore indoor places. Urban air pollution affects our health. I suppose that's probably why you turned up here tonight, because you know that current modern urban environments aren't particularly healthy. Most of the pollutants that damage our health in urban areas come from burning fossil fuels. Ninety per cent of them come from our dependence on fossil fuels for energy and so on.
Things that might affect our health are things like oxides, carbon dioxide. You all know carbon dioxide. It's what we exhale. High concentrations of carbon dioxide damage our health quite significantly. Carbon monoxide produced by flueless gas heaters and things like that, it's well known that's a damaging compound. Nitrogen oxide is one of the main pollutants produced by internal combustion engines. What functionally happens to nitrogen oxides is that they end up turning through a series of reactions into nitric acid in our lungs. You can envisage the outcomes of that process.
Sulphur oxide is similar. The end outcome is sulphuric acid in our lungs. These components are in quite high concentrations in urban areas. Secondly, inefficient or incomplete combustion in internal combustion engines as well as a lot of other processes related to the urban lifestyle, release volatile organic compounds. Here we're talking about hydrocarbons of various types. The worst four are probably the BTEX group, the big four of hydrocarbon pollution. Benzene, toluene, ethyl benzene and xylene.
The main health effect related to these compounds is cancer. They're carcinogenic. Okay. They have health effects in lower concentrations as well but the main outcome is cancer. Another type of air toxic that's produced is polycyclic aromatic hydrocarbons. Once again from incomplete combustion. Once again these things cause cancer. There are over 100 compounds that are classed as polycyclic aromatics. All cancer causing. Particulates are small solid or liquid particles that float around the air and make their way into our lungs.
When we talk about particulate air pollution, we're usually talking about particles less than 10 microns in diameter. A lot of these particulates might add or absorb volatile organics. So not only are you inhaling particles, you're also inhaling hydrocarbons attached to those particles. Growing evidence, a growing body of evidence shows that particulates have a really negative effect on lung function. If you're an asthmatic, they can exacerbate asthma. If you've got cardiac problems they can affect cardiac problems.
Chronic obstructive pulmonary disease is greatly exacerbated by high concentrations of particulates. They're a big problem as well. Ozone. We all know that ozone in the upper atmosphere is a good thing. Of course it protects the biosphere as a whole. At ground level it has quite different effects. Ozone is produced by a reaction between nitrogen oxides and hydrocarbons under the influence of sunlight, at ground level. To summarise the effect of ozone on human health, I guess if you think about what sunlight does to your skin, ozone does a similar sort of process to your lung tissue. So it burns, oxidises and so on.
So outcomes once again, greatly exacerbating asthma, reducing lung function and so on. The results of all of that, two to three million deaths per year worldwide have been attributed to urban air pollution. Six hundred thousand of them are from China. China tend to do a lot of cooking and urban heating with open coal fires. So a lot of them are in China. If we extrapolate to Sydney, 1400 to 2000 deaths a year in Sydney that are directly associated with poor urban air quality. It's not an insignificant thing. I mean two to three million a year is up amongst influenza with death rates.
This is a major issue. Twelve billion dollars a year in health costs to Australia, those figures are old. So you can comfortably increase this number by a large margin. This is not a minor issue. It's a major problem that we're facing. Aren't you safe indoors? You've got the air-conditioning system on, so all's good. Unfortunately, the opposite is the case. Indoor air is almost always more polluted than outdoor air. Usually we'd expect about two to 10 times higher. In the room you're in now it's probably close to five times more polluted than the - don't' leave, but it's probably - sorry, I wish I hadn't said that now.
It's probably about five times more polluted than outdoors. Air-conditioning doesn't save you. There are filters in common air-conditioning systems and we've been through the air-conditioning system of these buildings. They have a filter. They do trap some particulate matter. They'll take out coarse particles. They'll take out some fungal spores. Anything gaseous passes straight through. They'll strain some things out of the air but they don't improve air quality at all.
Then we come to what happens indoors. As well as the outdoor load of hydrocarbons and volatile organics, we add more indoors. They're emitted from plastics, the carpet, the chairs, the clothes you're wearing. They all emit volatile organics which add to the outdoor load that we're getting through the air-conditioning system. Everything we do, computers, copiers, they all put out organic materials. Of course more carbon dioxide from us breathing as well. If you're using unflued gas appliances, I'd probably recommend you stop doing that. They're not a healthy appliance in any way.
Certainly we produce a lot more CO2 from us breathing. Some sources of VOCs indoors, everything. I think I could summarise by saying everything puts out VOCs. Look I know that the industry has gone to a lot of efforts to reduce the VOC emissions from their products. The paints you buy now says in a lot of cases, low VOC paint. Okay. It's still paint. Sure, the VOCs are lower than they used to be but it's still made out of the same stuff. So it still emits VOCs. Epoxy floor covering produces bisphenol A in large quantities, a known endocrine disruptor.
Any epoxy produces materials. Furnishings, floor covers, the padding in padded chairs produces VOCs. Fibreboard or MDF releases large quantities of formaldehyde which is a carcinogen. So the things that our world is made of, release VOCs. So the effects of indoor air pollution, I'm not talking about the cancer end of the scale here. This is more the low background level of VOCs that we're all experiencing now. VOCs even at imperceptible levels, our perception level is about 500 parts per billion from the most common VOCs we see in urban areas.
So at levels lower than that. You can't smell VOCs in here now. No, it's all good. These are the levels we're talking about. Loss of concentration, headaches, eye, nose and throat problems, ever experienced them indoors? Of course you have. What was causing it? Were you having a lazy day? It's our air quality. At the moment Australia is having a look at its air quality standard. It used to be a maximum of 500 parts per billion for total volatile organic compounds. Five hundred, as I said, is about the level that you can perceive. However, new evidence particularly from Europe showing that a lot of people can show ill effects down to 200 parts per billion.
When we're talking parts per billion, we're talking small numbers here but these are very toxic materials. High carbon dioxide above 800 parts per million, in this room at the moment, the concentration of CO2 will be 800 parts per million. The air-conditioning system in UTS has got a cut off designed into it that when the air reaches 800 ppm it starts replacing the air at a higher rate. In most buildings they're 1000 parts per million. UTS seems to have a notion that people in universities should think more clearly. I don't know if it works. Tell your first year teacher I'm not sure it works.
We're running at 800 now. Loss of concentration and drowsiness. Sorry. You know these effects, don't you? It's not you. It's the room. These are the main causes of sick building syndrome. There were myths going around for many years that certain fungal species, particularly stacci botrus [shartadem] was causing sick building syndrome and people had to clean up the mould. That's been dismissed utterly. These are what causes sick building syndrome, low air quality. So plants can fix the whole thing up.
Other people's research have shown reductions in nitrogen oxides. An English study a few years ago showed that if you have six indoor plants in your house, the nitrogen oxide levels are reduced to about a third. So they make a difference. Sulphur oxides, a Korean study has found that pretty much any type of indoor plant they studied had a major effect on reducing sulphur oxides. Nitrogen oxides and sulphur oxides act as plant nutrients. The plants deal with them through their own metabolic systems.
Ozone is a little bit different. Plants unquestionably reduce ozone concentrations. The way they do it is almost sacrificing themselves. Ozone affects plants the same way it affects us. It still damages them and does them ill health, okay, but being structurally simple organisms, the plants tend to recover more easily than we do. So you put a plant, it gets sick and you don't get as sick as a result. Particulates, there's good strong evidence that shows that particulates are reduced by plants. The way they do it is by having a complex three dimensional structure, they produce a large still air zone around the plant which causes particulates to drop out of - deposit out of the air stream.
Quite a convincing bit of evidence. Noise is a similar effect. Because of the complex structure plants tend to act as an effective sound buffer to reduce noise. There's good evidence, good scientific evidence for all of these things. What we specialise in is VOCs, carbon dioxide and carbon monoxide is coming soon. That'll be the next thing we look at in more detail. We've got quite a lot. We've got a massive amount of evidence on VOCs, an increasing amount of evidence on CO2. So they're the main ones I want to talk about today.
For VOC removal we've done most of our research in test chambers which I'll show you in a moment. We've looked at 15 indoor plant species. That number is about to grow to 21. We've got a lot of new species in which we're about to test. They all work, I'll tell you that now. Because the first question that someone asks is, what's the best plant? There's the best plant, okay. They're all fine. I don't know about cacti but they're all fine. We've looked at four VOCs, four organic compounds, benzene, toluene and xylene from that BTEX group of the most well-known toxic materials.
We also looked at hexane. It's another VOC of health importance around the world. It also has a very different chemical structure to the other compounds. So we wanted to see whether the plants had the same effect on a markedly different material. A very brief summary of our method. We stick a plant in our chambers. Our chambers are non VOC absorbent Perspex. They're sealed. They have a light, a fan to allow the VOC to circulate and a temperature coil to make sure the temperature still stays at room temperature.
We inject the dose of VOC as a liquid through a gas type syringe through the front, let it equilibrate, so we allow this material to evaporate, fill the chamber. We then go and take air samples using a different type of syringe and measure the concentration of VOCs by head space gas chromatography, if you're interested. We put it in a machine that tells us what happens. What we then tended to do over the years is to go and wait until the first concentration of VOC has been removed. When it gets down to about zero we do it again. Give it the same dose again. Then again.
We find after three runs the removal rate is at its absolute maximum. So we've got a nice base by which we can compare different species. We've got a million of these graphs now. I can press - show you a thousand of the things. I thought I'd just summarise the results we get with one. So this is the ZZ plant, Zamioculcas zamiifolia. It's a very popular indoor plant in recent years. We put quite big pots in this. It was 300 ml pots. The way this graph works is at time zero we put in five parts per million of benzene. We put in 10 times the exposure limit. We call that 100 per cent. After three days it was down to close to zero.
The reason why this didn't go exactly to zero was because of a correction factor that we have to apply because of some leakage through our chambers. Functionally it does remove it to zero. Three days it's gone. So we give it another dose of five parts per million. You'll note here the second dose is clearly removed more quickly. So there's a learning phase in this process. The more exposure these plants have to VOCs the more efficient they get at removing it. Someone obviously went away for the week-end here. Jason. Then we try it again and give it a final dose.
The final dose is we've found the maximum rate at which the VOCs can be removed. We can do this another 15 times and that curve will look exactly the same as dose three. We have done it another 15 times to make sure. The final dose, the way we've been running this experiment recently is to give it five times the dose we did before. So this is 25 parts per million. This is a very high, very toxic concentration. This is like putting a petrol bowser up your nose. You're not going to survive in that chamber for very long. You're going to be sick.
Two and a half days later it's gone to zero. So there's a system here. This works. This is a very effective system at removing VOCs that doesn't cost anything. You put the plant in there and it removes the VOCs. Overall all species had very similar removal capacities and rates. There's a bit of variation between plant species, not really significant. If you put a plant in your room it removes the VOCs. We haven't done a cactus yet though. We haven't done a cactus yet, so sorry if you're trying to sell cacti, Ray.
All the VOCs tested, that was for benzene that graph I showed you before, hexane, xylene, exactly the same graph. They clean up everything. All species were stimulated by the first two to three doses. So that's what I mean by slow, faster, faster. After three doses they're going at their maximum rate. Subsequent doses are removed in 24 hours. Once a plant is trained or there's been experience with a certain VOC, 24 hours that concentration has gone. Our rates increase with increasing dosages. We got silly with this at one stage and we went up to 1000 parts per million.
Now 1000 parts per million in those Perspex chambers is a big pool sitting on the floor. I mean it was just silly. It's the sort of environment in which any animal would die within minutes. Forty eight hours it's gone. Did it again. Twenty four hours it's gone. So concentration doesn't seem to matter. The plants just get rid of it. Removal rates equal in light or dark. We turned the lights off and wrapped the chambers in plastic. It works exactly the same. We then went one step further and we took the plant out of the pot. It still works just the same.
So why have you come to a talk about plants and Fraser's saying the plants don't matter. Well, there's a reason for it. We did a bit of research about a decade ago that showed that the plant itself has a limited role in removing VOCs. What the plant does is support a community of bacteria in the potting mix. The bacteria use the VOCs as food. So much - as appealing as a pot of potting mix in the corner of your office is, it really does work better if you put a plant in. The potting mix will remove VOCs for a while. It'll get tired after a while and stop functioning.
You stick a plant in it, the plant feeds the bacteria, everybody's happy and it works forever. Okay. So it's really a bacterial process. We're confident to say any indoor plant species is likely to remove VOCs. We've done enough samples to show that this effect is wide spread. So a brief comparison of removal. We've said the time for removal of 80 per cent of a dose of five parts per million. We've stuck with 80 per cent because the curve tends to start tapering off after 80 per cent is removed. So we've got 80 per cent as a nice even basis for comparison amongst plants.
See Aglaonema 19 hours to remove 80 per cent. ZZ plant 20 hours, Mother-in-law's Tongue, sensitive area 22 hours. Devil's Ivy, 24 hours. Philodendron 28. Chamaedorea, the parlour palm which is there, 29 hours. You can see there's a bit of variation, all around that 24 hour mark. So it's about the time scale we're talking here. We have received some criticism over the years in literature for limiting our research to test chambers. A lot of people say test chambers are nice but they're not the real world.
So we fixed that problem and we've expanded our research a few years back to a real world, a field study for offices. Our question was how many plants are needed in a typical office to keep the air clean? Do you need a jungle? I mean our test chamber is this big. It's got a big plant in the middle of it. How many plants do you need in an office? In our first office study we had three UTS buildings and we took outdoor samples as well for comparison. These buildings, two of them had old fashioned air-conditioning systems and one of them was not air-conditioned and that's significant. I'll get back to that later.
Sixty offices. We started off with zero, three and six plants under the premise that we mightn't need a significant number of plants in an office to remove VOCs. Fifteen per treatment. We used Dracaena and Spathiphyllum as the test species. They're very common indoor plant species. Sampled for six weeks. Took the plants out and randomly reassigned them to the offices again to do a cross-over style design. Sampled weekly. We deliberately sampled for VOCs and CO2 but our instrument also measured temperature, humidity and carbon monoxide.
So we collected that data as well. That was a really interesting thing to do. These are our results. The first graph. This column here is the ambient VOC level. So that's the VOC level outdoors. The first thing you'll notice is that indoor air is definitely more polluted than outdoor air. There are higher concentrations of VOCs indoors than out. We weren't making it up. Three and six plants clearly removed significantly more VOCs than no plants. So rooms that had three plants, had six plants, had lower concentrations of VOCs than offices that had none.
So it works. The second graph is we did something a little bit circular here. We said okay, what happens on bad days? So on days where the VOC concentration in our no plant reference offices was over 200 parts per million, what happened then? You can see the results. When the VOC concentration is higher the plants work harder to remove VOCs faster. So once that concentration starts to get up the plants work better to remove that concentration of VOCs. So they respond to the concentration in the environment. Ready to go.
We also found that three or more plants reduced CO2 by 10 to 25 per cent. Significant reductions in carbon dioxide. Carbon monoxide by up to 90 per cent. We haven't followed up on that yet. That's coming. That's where we're up to. So CO, we'll put a question mark next to and we'll get to that in the future. Okay, so three or six work. A lot of people don't want six plants in their offices. Some of the smaller offices were rather cramped with six plants in them. So we had to ask the question. Three work. Six work. What about one and two? Do they work as well?
So we did another office study. Same design except we used zero, one, two or three plants. Now comes the problem. All the buildings had modern air-conditioning systems in them, with that carbon dioxide set point. We went and did the study again and what we found was there were minor reductions in volatile organics in carbon dioxide but the differences were nowhere near what we got before. The air-conditioning system was cleaning the air very effectively negating the effect of the plants. So what we were doing was using a heap of electricity, a lot of energy to clean the air with a machine that could have been done for free with a plant.
So I put it to you that air-conditioning systems are really just energy guzzling alternatives to indoor plants. Really. I mean sure the air was clean but at a cost. With the plants there's no cost. That's what we've run with. So clearly plants can be used to lower building energy costs. Plants do the work for you. There's no need to turn the power up to get the air-conditioning to clean the air. The plants will do it for you. That will in turn reduce the carbon footprint and of course move towards that goal of sustainability.
A lot of horticulturalists are working on green walls. Most of the use of these green walls is aesthetic. They look nice. I think what we're going to find is that buildings that have these put in, just co-incidentally get really low air-conditioning bills. I think this is going to be the future in a lot of buildings. When this research gets more widely known and you're a part of that process by turning up and listening to this talk, that's going to greatly reduce our energy use in cities.
We then moved on to carbon dioxide. Carbon dioxide was clearly something that was important being our primary anthropogenic greenhouse gas. A very brief background on photosynthesis for the non-scientists in the audience. What plants do to live is that they use the energy from sunlight to combine carbon dioxide from the air, water from the soil to produce oxygen which we breathe and glucose which is plant food. So plants are machines that eat carbon dioxide to grow. They don't eat food. They eat CO2. Photosynthesis only happens by the green parts of plants. They need light. They need the right sort of light.
So plants need the correct wavelength and intensity of light to photosynthesise. The rates of uptake depend on the light intensity. It makes sense. More light, more photosynthesis. Only up to a point though. If you give a plant too much light it starts to get sick and thinks I don't want to photosynthesise anymore. It'll actually start slowing down. So there's an optimum level of light for all plants. Species idiosyncrasies. Plants have different favourite light levels. Individual species have different favourite light levels. Individual plants prefer different light levels.
We've had some very strange occurrences where we've had a plant, measured it, got another plant, done exactly the same thing, got a completely different result. When you look back and worked out what you did, it's just we picked the plant up, we put it on a bench and then moved it back into the chamber again. That's it. So we tend to think that personality is something that animals have a mandate on. I put it to you that plants have got something akin to a personality as well. They do behave in that way. You treat an individual plant differently to another one it behaves differently.
We haven't followed that line of research at all and don't intend on following it at all. Shade tolerance. Indoor plants tend to be rain forest floor plants. They're the plants that work best in indoor settings. So indoor plants tend to be quite shade tolerant by their nature. That still varies amongst species. This plant is just stupendously shade tolerant. For some reason that one just because of its evolutionary history is much more tolerant of low light levels than a lot of others. Foliage area. More leaves, more photosynthesis. Leaf age. Mature leaves tend to work better than young ones. The same as people. Mature ones work much better than the young ones. That's Jason again I'm talking to.
Potting mix, moisture content, more water, more photosynthesis. That makes sense. Too much humidity - I'm sorry, not enough humidity tends to slow photosynthesis down. When humidity is low the plants tend to close up their stomata, the pores in their leaves and gas exchange slows down. So really low humidity is negative as well. CO2 concentration, more CO2 more photosynthesis. It makes sense. Once again up to a point of course.
This data is preliminary. We haven't synthesised all our data yet, but once again we have now got, thanks to our junior assistants, 100 of these graphs for different plants in different light intensities. This one is particularly good at showing the pattern that we've found. Per cent change from initial. One means 100 per cent. So that's the ambient CO2 concentration, about 400 parts per million in Sydney at the moment. If we give that plant a light intensity of 30 microeinsteins that is equivalent to probably sitting underneath the spotlight in the middle of the room. It's a bright indoor light level.
This is carbon dioxide level over time in minutes. Nothing happens. The plant sits there. No photosynthesis occurs. Turn the light up to the optimal level for that plant. In this case it's 200 microeinsteins. That's not silly. We haven't got a flood light on this plant. It's nowhere near say a tropical aquarium light intensity. It's just a very bright indoor light. Sixty minutes, CO2 goes from 100 per cent down to 10 per cent in that chamber. Fantastically rapid rate of CO2 removal if the light intensity is appropriate. This 200 microeinsteins isn't silly at all.
With modern LED technology we can get that set up at a very low energy draw. Nothing like the draw of the air-conditioning systems that's being used to replace them. Moving on then, it's been proposed that we're actually killing people by promoting indoor plants, because everybody knows when you put an indoor plant in your room, mould spores come off it and get into your lungs and kill you. When this was proposed to us we got a little bit upset and thought well, we don't want to kill people. So we went and did an experiment like scientists do.
We went - and as part of that office study that was going on, we took air samples using a mould spore sampler. That's something like a reversed hairdryer. It sucks in a known volume of air and deposits the spores over a fungal growth medium, similar to agar. We did monthly samples for 12 months. What we did was when we got the spores out of this machine we put them on Petri dishes like this; grew them up like cladosporium herbarum here. Looked at them under a microscope and identified the species.
We got a very detailed laborious count of the fungi over a year in UTS buildings. What did we find? Well, there's our zero plant offices. About 40 fungal spores per cubic metre of air. So fairly low level. One plant in the office. I think if you look really closely you can see there's a few more spores. Three plants, once again there's a few more. There are definitely a few more spores if you've got an indoor plant in your room. That might concern you as long as you never go outside. Because as soon as you take one step outside you've got an order of magnitude more spores in your lungs.
So if you're extremely immunocompromised, you've had kidney transplant, liver transplant, something like that and you want to live in clean room conditions, don't over plant it. Okay. Anybody else in the world, air quality is better with plants, not worse. Probably more importantly, the mould species distribution wasn't changed by plants. It was proposed that the plants are producing species, particularly aspergillus fumigatus if you're interested, that causes human disease. We couldn't find it anywhere. Jason had thousands and thousands and thousands of samples and couldn't find it anywhere.
We tested that hypothesis objectively and we got no result. Plants improve air quality. The fungi are not an issue at all. Okay, that's my half. Thanks for that. Now Meg - I'm a scientist. I think some of that stuff's a little bit implausible sometimes. When we do the thousand parts per million in the chamber and it was gone in 24 hours you sort of go back and check the numbers, you know. Meg's stuff is even more weird, okay. Thanks. Thanks heaps.
Meg:Yes, as Fraser indicates, not only do plants clean air, there's more to this story as well. I want to talk to you about those other directly measurable plant benefits that have been researched around the world and including what we've done at UTS on direct health benefits produced by the plants. The things that I'll be talking about will be things like reducing sick leave absences and illness symptoms at work and things like the increases in performance and productivity and feelings of wellbeing and lifting one's spirits as well.
We get asked how can they do that, doubtfully, you know. Can it really be true? What I want to do is now take a two second retrospective of people plant relationships since our species was invented. Depending on which author you read, our history stretches back half a million to two million years, depending on when we left - when we became homosapien sapiens, wise man, or as some of our students say, smarty pants, naked apes.
Anyway, at guess what, a period of climate change when the world in that case was getting a bit cooler, when the forests were giving away to park land, savannah landscapes and it was apparently seemed to be among some species, advantageous to go out into the grass land, the shrub land and look for the food better there than to stay up the trees. Our ancestors knew all about fire and so on and they appreciated plants for the food obviously. They were just as dependent on plants as we are as their food source; for shelter and for shade and for safety from predators and as timber for fire as well.
They were hunter gatherers and became nomadic herdsmen. It was only 35,000 - only 35,000 years ago when apparently we started to settle, to corral animals, to plant seeds and grow plants and of course, then got a lot of other uses of plants, practical uses of plants. For fences, to keep animals in or out, depending on which animals we're talking about. To save the crops from the animals and so on, and for timber for things like tools and weapons as well as housing, boats and so on.
Fast forward then another 30,000 years or so and we have the rise of the big city states with huge irrigation systems, huge architecture that arose from irrigation systems no doubt in part. Guess what? The people showed an appreciation and it is recorded in the engravings on the temples in Egypt, for example, of ornamental plants, ornamental plants. That is plants that are of no practical use in all of those ways that I've just mentioned, but we like having them around. Why? Well, again in the ancient records, we know that higher levels of appreciation of plants come in. Ones that probably only homosapien sapiens can fully appreciate.
Those of relaxation and aesthetics and beautiful scents and feelings of peace and piety and poetry and things that Egyptian and Babylonian people were good at. The Hanging Gardens of Babylon apparently had over 200 species of ornamental plants. Then if we move on through the Roman period. They also appreciated courtyards and plants and so on. Medieval monasteries used them for purposes of poetry, piety, prayer and so on. Also for treating mentally ill people by giving them cloistered gardens to sit in.
We then move on to the period of urbanisation which started to - it was a period of mass urbanisation, started to occur only about 300 years ago with the industrial revolution and by the way, we couldn't really keep these long suffering, shade tolerant plants indoors until window glazing became common throughout the western world. Then they could be brought right inside or we could make conservatories to house them. In 1800 when that tenement in London may have been built, there were only five per cent of people living in cities.
Today there are over 50 per cent of people living in urban areas around the globe. Obviously there must be a number of real advantages in living in cities. Our life span has almost doubled in those 300 years. Employment and education are higher in the cities, usually, most cities. Infectious diseases have gone down because of improvements in sewerage and hygiene and medical technology. But there are a number of new urban diseases now.
Those associated with obesity and a sedentary existence that are linked with a number of constitutional illnesses of serious sorts that are a major concern to the World Health Organisation now around the world and to stress and depression which are seen to be in the next 20 years, among the major illnesses besetting humans in the urban environment. Well, what's happened is, among other things, a huge reduction in green space in most of our lives. So the green space that is represented by parks and gardens in the cities are much appreciated and well used as far as possible.
A health promotion journal based from Oxford University said and I quote: The movement of people from rural to urban environments has facilitated their disengagement with the natural environment. Oxford University possibly talks like that all the time. And the protective forces and factors of nature for health improvement and sustainability have been reduced by our diminishing regular contact with nature. A Singapore architect Ken Yeang said in the mid '90s, and it sort of summarised what environmental psychologists and evolutionary biologists sort of agree on.
He said - and Singapore is a good case in point of course. The fact that people are constantly moving into new environments unconnected with the natural environment - in other words, the built environment - tends to give the impression that they're enlarging their range of their evolutionary past. This is an illusion because wherever humans go they can only function to the extent that they maintain a micro environment that is similar to the one from which they evolved. Zoos, you talk to zoologists and vets at the zoos these days, they say they want to provide their animals, each of their species, with their particular environment of evolutionary adaptation.
The television thing says what about me? What about us? What about us. We now know from research, that half an hour spent in the garden at lunch time will lower the blood pressure by about 10 points. It will reduce feelings of anxiety and depression because people have done surveys before and after the lunch time break with subjects who are willing to answer questions. There is also real financial hardnosed evidence about our intuitive affinity for greenness that don't rely on psychologists and evolutionary biologists.
For example, the real estate motto continues to be, location, location, location, doesn't it? Where is that location? I bet it's got plants in and a bit of water. Probably for the highest prices, right. Who gets the corner office in those high rise buildings? Usually not the girls in the typing pool, aye? It's usually the seniors. The top three family sites on the web are gardening, ideas for week-end getaways and fishing. All back to nature escapes, right. Okay, but we spend 90 per cent of our time indoors as Fraser was saying. Sometimes even listening to scintillating lectures.
We don't have a view in here, do we? Even views of green space, space at all and green space, help. There's a lot of evidence from this, from a number of studies, most of them done in America, but some from other parts of the world as well. In the early 1980s someone -Moore - looked at the records in prison of those who - those prisoners who were well behaved and poorly behaved, who were rambunctious who needed a lot of attention and medication and so on. They found in that prison that people who could have a rural landscape out the window of their cell had much better behaviour and much lower pain killer need than those who didn't have views at all in their cells.
A few years later and you've possibly heard of this one, Roger Ulrich looked at rates - again looking at hospital records, the rates of release of people after surgery, after gall bladder surgery, which was in those days in the 1980s, surgery where they kept you in for a week or so. He found that those who looked out on the planted landscape of the hospital got out nearly two days ahead of those that looked out on the brick wall, although you'd think the ones who looked out on the brick wall would want to get home sooner.
Then in the later data again, two other redoubtable environmental psychologists in America, Kaplan and Kaplan found that staff at work who had views reported fewer illnesses and had fewer headaches than those without. A study of staff in a wine factory in France found that staff with windows of natural views had higher feelings of wellbeing, significantly lower stress, and this would be on survey work with the staff, and fewer intentions to quit. I like that one. Something very French about that one.
In 2005 and 2008 in Japan and in Melbourne with [Mellor] and colleagues at - I think it's Monash University, but I'm not quite sure - they looked at students or reported students who had - university students who had residential digs that had views of gardens did better on their test scores and examinations than those who looked out on city scapes, hard city scapes with just traffic and brick walls again. So views are important, but we all know that if you're in an office situation you're often not near a view. You're not even within sight of a view.
Another study in the USA looked at how views or indoor plants affected job satisfaction ratings overall. They did this with an online survey. They got 450 or so respondents. They didn't stress the plants. They said how was your job satisfaction? What's your work like? Is your boss alright? Are your leave conditions okay? Is the worker doing okay and is your desk okay and so on. By the way, do you have a view or do you have plants on your desk etcetera. Not surprisingly they found that the top rating people for job satisfaction on all those 10 criteria or so were those that had both plants on their desk and a planted view.
The next happiest people, the ones who came in second, were those that had plants on their desk rather than planted views alone. The unhappiest were the ones who had neither. We're surprised, aren't we. Why did the desk plant people come out on top of the ones with views? Presumably because of the immediacy of the living green that was near them. Alright. Let's look at indoor situations per se. Quite a lot of research has been done on the effects of plants in the room on - or plants in the office on illness and absenteeism.
The pioneer study was done in Norway by a lady called Fjeld and colleagues. They put plants in the radiology department of the public hospital in Stockholm or somewhere that was down underground as it tends to be. They found that the sick leave rate dropped from over 15 per cent to under five per cent which is an over 60 per cent increase in attendance of the staff. That was maintained over a long period of 12 months post planted period.
She and her colleagues also did a school pupil one and found absences were reduced by - illness absences reduced by over 20 per cent. They also looked at those who were still standing, as it were, and found that those in offices with plants had fewer coughing and wheezing fits and fewer complaints of dry eyes, nose and throat. Now those ones might have to do fairly closely with the clean air effects of the plants and the uptake of particulates and so on from the air. They also perhaps had a psychological effect of lifting your spirits.
How do you measure a lowering imperception of pain? How do you apply pain? Well if you've got psychology students who are prepared to do practical work with you, you've got a good lot of participants who are eager to get five per cent on their marks. So you get them into a room which may or may not have plants in. You quiz them or chat to them about any other aspect of psychology than plants. You've got their hand shoved in a bucket of iced water. They found that the length of time before the student goes can we stop now, it was up by 25 per cent.
I've mentioned that blood pressure has been lowered by 10 millimetres of mercury which isn't nothing. They were the reductions in negative symptoms. Now what about improvement in positive symptoms? Again there have been many tests, a lot of them done on those same psychology students about completion of computer tasks or marks on computer tests and so on. Again with plants there or not there for the various groups. The plants aren't mentioned or referred to in any way. Creative thinking exercises, how many words can you think of related to Java, you know.
Those who get up to 35 win, sort of thing. Multiple choice quizzes of various sorts and college examinations. Turning to medical evidence of the effects of indoor incarceration, there's somebody in the green building council in Sydney refers to the built environment as - air-conditioned ones, as neo gas chambers into which we have to put the air and so on that we do. Part of it is the over-crowdedness and the lack of privacy and so on. We know that work place stress certainly reduces productivity but stress also gives to illness.
I try to illustrate confusion, hostility, fatigue and despair. So we ask ourselves can indoor plants directly reduce stress? Now, as we may have said at the beginning, we are not psychologists. So for this particular study we got Professor Ashley Craig who's now at Sydney University but used to be at UTS, psychologist with 25 years' experience in the field, to lead us in this component. In the office study that Fraser was talking about, in the second office study, we also administered two nationally validated - internationally validated questionnaires which have been used for over 30 years, all of them in psychiatry and psychology for patients or sub-populations of various sorts.
We had the same for plant treatments and the control group without plants. We administered the survey as the plants went in and then at the end of the trial before we removed the plants. We were astounded by the results. We knew that these surveys were supposed to be very sensitive in how they could pick up changes of mood states, but we certainly didn't expect that depression would be - feelings of depression, it didn't strike us that the staff were very depressed in the first place, but it picks up mild effects that we tend to ignore or deny as we go about our daily job.
All of those negative mood states, total negativity which they did by summing it against a positive emotion that they called vigour, which was enthusiasm and get up and go-ness. Towards the end of semester the no plant group went up by 20 to 40 per cent in various parameters. Why? Because the exams were coming. They had to be set. All of the other work had to be marked. The students had to be got out of the office. You know, all of that. It does get a little bit stressful towards the end of the semester.
This one simply shows the difference between the four groups of - the four treatments with plants and the one at the end which - is that working? Yes. This one is the mob without plants. You can see that when we started, a lot of the people who got plants, we were naïve in this. If people came and said please, please, can I be in it, please, please can I have a plant? We said sure. We put them down in the first group and so on. We got people who obviously were badly in need of a plant. You can see that the level of all of those negative things went right down.
There wasn't much difference between whether you had one or three desk plants, one or two floor plants. Sure, the extra might have made some slight difference, but imperceptible. Whereas that might not look much of a change, but those with no plants certainly went up. So what we're saying is for the purposes of lifting one's spirits, just one plant is enough. But don't leave it at one because if you have more plants in, the air cleansing purposes are going to be better. I suppose one plant is infinitely more than no plants. In some offices that's perfectly obvious.
Then we were inveigled into doing a pioneer study with a mate in Queensland who heard me talking about some of this work one day. I said there was a Korean study of two students at high school. One who had plants. One grew plants and one didn't. The ones with plants from the very day they went in were better behaved, had fewer calls to the principal's office and did better on their tests than the other one. Our mate John Daley said, could have been the teacher, couldn't it? Yes.
One treatment, one sample does not a proper experiment make. So he said he could get us and did, three independent schools in the Brisbane region, 15 classes of six, seven grade children. We had three plants in those class rooms that were planted and of course none in the reference group. We had standard spelling and maths tests administered and science in one school. We got again an increase in productivity of 10 to 14 per cent, an increase in performance that is, in tests of 10 to 14 per cent.
If we take the example of the maths, we tested halfway through the period. I haven't put the first one in, but halfway through the period and then at the end of the period. Both the green ones with the plants and the black ones without, they went up. They are at school after all, so they're supposed to be getting better. The ones with plants got better-er, didn't they? Why is it so? The environmental psychologists say that nearby plants, even if we don't notice them, first of all relieve tension fatigue.
If we are actually concentrating on something at work or at home, that is giving all our attention, part of the energy, part of our brain energy that we're using there is stopping it thinking, but I have to go and get something for dinner and I've got to pick up the kids after ballet. So you stop yourself thinking that as you're concentrating on the job in hand. You're trying to anyway. That takes effort. This feeling of awayness is a sigh of relief. You don't have to even notice the plant for this to happen. Just it's being there and you know it's there is enough.
So it resets our calm button because it reduces that attentive fatigue. Then we're asked, but why is that so? How come that effect can happen, that psychological effect? Well again the environmental psychologists and the evolutionary biologists agree on the proposition that - and this is why I mentioned the savannah in the first place. We are intuitive - they say we are intuitively hard wired to regard living greenery as somehow the place where we belong. So consequently we need living greenery in our immediate environment for optimum wellbeing.
If we are in a building 90 per cent of our time, then we've got to bring plants in with us to do it. In other words, you can take the apes out of the savannah but you can't take the savannah out of the apes, aye? So we then checked all this data against the New South Wales government work place guidelines for an optimum indoor environmental quality on those criteria. We found that the indoor plants can contribute to virtually every one of those. That leads us to - I mean it's more reinforcing when you can line up against something that's very cut and dried and say yes, well plants do help with all of those criteria.
So in summary indoor plants are good for you. They not only look good. I was talking to someone before the lecture began and she said, where I work which is a big government department that ought to know better, we're not allowed to bring our own plants in. There's a few model plants scattered around but not many because they cost too much and they're maintenance is too high. No they're not. The plants cost very little compared with all of the other expenses of office buildings. Even at home they cost very little. They cost very little maintenance.
It's been estimated that whether you bring in the plants yourself or you get a hire firm like Ambius or any of the others to look after you, they cost about the cost of a cappuccino or something. Or to put it another way, I've looked at work place productivity of increases of 12 per cent or so and school performances of 12 per cent or so. If you get a less than one per cent change in productivity you've more than paid for the plants. The main thing is you've got happier people. Much, much, more important. Of course as Fraser says, they can also be used to lower air-conditioning costs and the carbon footprint of the city and hence the goal of sustainability.
Now I want to give some acknowledgements that we must give at this stage. This is the plants and indoor environmental quality group. We like to call it to PIQ group sometimes. Start a plant on your desk or your kitchen sink.
29 June 2011
The truth about indoor air quality and how plants really clear the air and calm the mind.
Over 80% of Australians live in urban areas, spending 90% of their time indoors at work, school or in the home. Health costs of urban air pollution (UAP) is estimated by CSIRO at about $12 billion per annum, and NSW Health estimates UAP causes up to 2000 deaths each year in the Sydney metropolitan area alone.
Did you know that indoor air pollution is 2-10 times higher than the outdoors or that indoor plants reduce symptoms such as headaches, sore eyes, loss of concentration and feelings of depression? Indoor air is high in CO2 with harmful pollutants emitted from indoor 'plastic' or 'synthetic' furniture, furnishings and equipment like computers, copiers and solvents.
Professor Margaret Burchett and Dr Fraser Torpy report UTS research findings that prove how efficiently indoor plants can remove pollutants, cleanse stale air and reduce symptoms such as headaches, sore eyes, loss of concentration and feelings of 'stuffiness'. Discover the health benefits associated with the presences of indoor plants in raising spirits, reducing feelings of stress or fatigue and improving work productivity and performance.
Test Tags: biomedical science, house plants, air pollution
About the speakers
Professor Margaret Burchett is a plant environmental toxicologist, with research interests in the benefits of plants in urban areas - their responses to pollution and their capacities to reduce and remediate pollution. Over the last 15 years she has led research in the UTS Plants and Indoor Environmental Quality Group focusing on the uses of potted-plants to reduce urban indoor air pollution and promote health and wellbeing for building occupants.
Dr Fraser Torpy is a microbial ecologist and biostatistician who has worked alongside Professor Burchett in the UTS Plants and Indoor Environmental Quality Group for over a decade. His primary research interests are the microbial and ecophysiological processes involved with the potted-plant effects on indoor air quality and the analysis of ecological data.
UTS Science in Focus is a free public lecture series showcasing the latest research from prominent UTS scientists and researchers.
Dr Dominic Hare and Dr Blaine Roberts examine how cutting edge analytical technology is providing new insight into how the role of trace elements in normal physiology is being applied to studying devastating diseases in humans.
Professor Liz Harry discusses the secret lives of bacteria. She explains the vital role that bacteria plays in sustaining life on earth and the latest research that is being done to find solutions to this serious threat to human health.