Sunday, 25 August 2013

How to grow fresh air

On Wednesday we finished off with a piece of advice about clean air and indoor plants. Tonight we wanted to follow up on that comment.

What's the problem with indoor air?

"The indoor environment is five to ten times more polluted than the exterior"
(1994 CSIRO review)

"In recent years, comparative risk studies performed by the US EPA and its Science Advisory Board have consistently ranked indoor air pollution among the top five environmental risks to public health" (US EPA, 1993)

The average Australian spends 90 percent or more of their time indoors. Despite this, relatively little research has been done on the quality of air in our homes, schools, recreational buildings, restaurants, public buildings, offices and cars. According to the Commonwealth Government many chemicals present in indoor air environments have not been thoroughly tested and little is known about their long-term health effects. Even less is understood about the health effects from constant exposure to mixtures of these chemicals.

Peace Lilly
Can indoor plants really make clean air?


There is a wealth of scientific evidence that supports the beneficial effects of indoor plants including a large NASA programme.

Plants can remove toxins from air, up to a staggering 87 percent of volatile organic compounds (VOCs) every 24 hours (according to NASA research). Modern climate-controlled, air-tight buildings trap VOCs inside. VOCs include substances like formaldehyde (present in rugs, vinyl, cigarette smoke and grocery bags), benzene and trichloroethylene (both found in man-made fibres, inks, solvents and paint). The NASA research discovered that plants purify that trapped air by pulling contaminants into soil, where root zone microorganisms convert VOCs into food for the plant.

When you breathe, your body takes in oxygen and releases carbon dioxide. During photosynthesis, plants absorb carbon dioxide and release oxygen. This makes plants and people natural partners, as indoor plants can increase oxygen levels.

What are some of the other benefits of indoor plants?

... During photosynthesis plants release water vapour which increases humidity of the air around them. By placing several plants together you can increase the humidity of a room, which helps keeps respiratory distresses at bay.

... According to researchers at Kansas State University adding plants to hospital rooms speeds recovery rates of surgical patients. Compared to patients in rooms without plants, patients in rooms with plants request less pain medication, have lower heart rates and blood pressure, experience less fatigue and anxiety, and are released from the hospital sooner.

... The Dutch Product Board for Horticulture commissioned a workplace study that discovered that adding plants to an office decreases fatigue, colds, headaches, coughs, sore throats and flu-like symptoms. 

... In a study by the Agricultural University of Norway, sickness rates fell by more than 60 percent in offices with plants.

... A study at The Royal College of Agriculture in Circencester found that students demonstrated 70 percent greater attentiveness when taught in rooms containing plants.

Still not convinced? Check out this four minute TED talk.

How are we growing our fresh air?

With indoor plants of course! Here's a couple of photos of our fresh air generators around the house.

Which plants are best for clean air?

Bill Wolverton (of NASA fame) wrote a great book called "How to Grow Fresh Air", a fantastic resource for anyone interested in this topic. The best indoor house plants to grow fresh air include:

  • English ivy (Hedera helix)
  • Spider plant (Chlorophytum comosum)
  • Golden pothos or Devil's ivy (Scindapsus aures or Epipremnum aureum)
  • Peace lily (Spathiphyllum 'Mauna Loa')
  • Chinese evergreen (Aglaonema modestum)
  • Bamboo palm or reed palm (Chamaedorea sefritzii)
  • Snake plant or mother-in-law's tongue (Sansevieria trifasciata'Laurentii')
  • Heartleaf philodendron (Philodendron oxycardium, syn.Philodendron cordatum)
  • Selloum philodendron (Philodendron bipinnatifidum, syn.Philodendron selloum)
  • Elephant ear philodendron (Philodendron domesticum)
  • Red-edged dracaena (Dracaena marginata)
  • Cornstalk dracaena (Dracaena fragans 'Massangeana')
  • Janet Craig dracaena (Dracaena deremensis 'Janet Craig')
  • Warneck dracaena (Dracaena deremensis 'Warneckii')
  • Weeping fig (Ficus benjamina)
  • Gerbera daisy or Barberton daisy (Gerbera jamesonii)
  • Pot mum or florist's chrysanthemum (Chrysantheium morifolium)
  • Rubber plant (Ficus elastica)

In addition here's some really basic tips:

  • Consider the amount of sun your indoor plants are likely to receive (some can survive on less light than others).
  • Keep watering schedules regular (use a calendar).
  • Periodically clean each plant with a damp cloth to ensure proper absorption of air particles and toxins.
  • Keep their soil replenished with organic compost. 
  • If possible use rainwater for your plants.
Finally if you’re looking for the plants of least resistance try Peace Lilies, Dracaenas or Golden Pathos, they're all quite hard to kill!

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