in Greener Homes on 11 September 2011
Greenery can revive the atmosphere at home
IF you live in a city or suburb, it’s likely the trucks and traffic sometimes make you gasp for breath. But Professor Margaret Burchett, from the school of environment at University of Technology, Sydney, warns that we can’t close our doors on poor air quality.
“According to the World Health Organisation, urban air pollution kills two to three million people around the globe every year,” she says. “But the amazing thing is that our air is more polluted indoors than outside.”
While Australian cities aren’t among the world’s smog-ridden worst, our population is overwhelmingly metropolitan. Eight out of ten of us live in urban areas, Professor Burchett says – and we spend nine out of every ten hours indoors.
In addition to the fossil fuel emissions that blow in from outside, indoor air typically comprises extra carbon dioxide, thanks to gas appliances and our breath, together with elevated levels of air toxics – volatile organic compounds (VOCs) from glues and synthetic materials.
“Inside our homes we have lots of petroleum-based products such as plastics, carpets, furnishings and electronics that are ‘off-gassing’ toxics,” Prof Burchett says.
These contaminants can cause health problems such as headaches, asthma, loss of concentration, wooziness and nausea.
But here’s the good news: we can freshen the air by bringing greenery into our buildings, places that Prof Burchett describes as “the most arid environment on Earth”.
Her team has been researching the way vegetation improves indoor air quality. They’ve found that pot plants can reduce the presence of VOCs by three quarters and diminish carbon dioxide levels by a quarter. “Plants help clean the air, there’s no doubt about that,” she says.
When it comes to vanishing the VOCs, it doesn’t matter what kind of indoor plant you choose – so long as you take good care of it. To reduce carbon dioxide levels, however, the more lush the foliage, the better.
“The bacteria in the potting mix are what takes up the toxics,” she explains. “The plant nourishes the bacteria, and the bacteria do the uptake. If you keep the plant healthy, it will keep its micro-organisms healthy and they’ll do the job – they’re the same bacteria that suck up oil spills, so this is just an entrée for them.”
In her living room, Prof Burchett has four pot plants (she had six, but two died recently while she was travelling – such calamities even befall the experts). Over- and under-watering are the most common ways to kill them, so she recommends testing soil moisture with your finger or a chopstick. To avoid mould growth, make sure you remove dead leaves and flowers.
“Have as many plants as you can, keeping in mind their level of shade tolerance,” she suggests. “Half a dozen will make a significant difference to your air quality and also to how you feel.”
Prof Burchett has been working with psychologists to study the wellbeing effects of plants in offices and schools.
“They lift the spirits,” she says. “They’re good for us psychologically. We’ve found that students perform better on memory and creative thinking tests. In offices, we found that one plant made all the difference in reducing in feelings of stress and hostility.
“When we’ve got greenery around us, it relieves our tension and fatigue.”