Need to reduce indoor pollution?
House plants will help you with that
ABC Health & Wellbeing
By Karen Burge | 9 Mar 2016
When you think of indoor health hazards, exposure to air pollution is probably not the first thing that comes to mind.
However, Dr Fraser Torpy, director of the University of Technology Sydney Plants and Indoor Environmental Quality Research Group, says the air circulating inside our buildings is often more polluted than the air outside, and this can have a very real impact on our health.
The air circulating inside buildings can contain a cocktail of polluted air that comes into a building from outside mixed with pollutants from indoor sources.
Heating, cooking, cleaning, smoking, perfumes and furnishings are all sources of indoor pollutants, which include carbon dioxide, carbon monoxide, nitrogen dioxide, sulfur oxide and volatile organic compounds (VOCs).
VOCs are a group of chemicals that are released from plastics and synthetics. In your home or office they can come from carpets, furniture, glues, computers, detergents and paints.
Just one plant in a room is fine, its capacity to remove those things is absolutely phenomenal.
Dr Fraser Torpy
These tend to build up indoors as they can be released from so many sources and because there is often poor ventilation.
A CSIRO report that measured the concentration of a range of pollutants inside homes and outdoors found that carbon dioxide, total VOCs, formaldehyde and carbonyls concentrations, for example, were all significantly higher inside than outside.
Carbon dioxide and VOCs are often to blame for lessening the quality of our indoor air, Dr Torpy says.
You don’t need a forest. Just one plant can help improve indoor air quality. (right image ABC)
While VOC levels in most dwellings and workplaces are quite low, a UTS study highlighted that even at low levels these pollutants can contribute to sick building syndrome, which has been associated with headaches, dry eyes, nose and throat, a woozy-head feeling and nausea.
Carbon dioxide can also have a similar effect. The maximum level of CO2 under Australian recommendations is 1000 parts per million, according to the UTS group. Yet being exposed to CO2 at levels above 800 to 1000 parts per million can produce feelings of stuffiness, loss of concentration and drowsiness. If you’re exposed to higher levels you’ll probably become quite unwell, but this is uncommon due to efficient ventilation.
“Almost all the carbon dioxide indoors is going to be human exhalation but because world carbon dioxide levels are increasing so fast the rate is now getting really seriously high. It’s very easy to get to a level indoors where you are going to start seeing symptoms, ” Dr Torpy explained.
Clearing the air
The good news is that indoor plants can remove VOCs 24/7 by absorbing and degrading air pollutants and releasing oxygen into the air as part of the photosynthetic process.
Interestingly NASA scientists back in the ’80s were early observers of the major role indoor plants played in removing organic chemicals from the air (specifically benzene, trichloroethylene and formaldehyde in their study).
“A lot of people are concerned about volatile organic compounds… If that’s what you are worried about then just one plant in a room is fine, its capacity to remove those things is absolutely phenomenal,” Dr Torpy explains.
“A medium-sized plant (anything above about 20cm) in a room will make really big reductions to those particular chemicals.”
Plants can also help manage carbon dioxide levels. Dr Torpy’s research group analysed the effect of indoor plants on air quality in workplaces and found that in offices with plants, CO2 levels reduced by about 10 per cent in an air-conditioned building and 25 per cent in a building without air-conditioning.
UTS has done a lot of work into different types of plants and have made comparisons on their impact on air quality.
“We found palms beat everything else for carbon dioxide. But when it comes to volatile organics everything is the same – it doesn’t matter.”
As well plants have been found to improve mood, and again you only need one indoor plant to start feeling the difference. In a three-month study of UTS office staff, participants with plants reported a reduction in stress and negative feelings by as much as 40 per cent. International researchers have found plants can help to reduce the amount of sick leave people take.
The next step in creating healthier indoor spaces, Dr Torpy says, will be green walling, making strong use of vertical gardens to bring out maximum air cleaning benefits.