Purification of Indoor Air Quality – Negative Ions & Plants

David Baggs, CEO and Technical Director

With most people spending up to 80% of their time in indoor environments, be it at home, in the office, at school or university, it's becoming more and more important to ensure our indoor environment is a healthy place. This is even more necessary as buildings become increasingly air tight and ventilation systems become closed loop as people rely increasingly on air conditioning in summer time. This closing up of buildings comes at a price indoor air quality reducing due to emissions from various sources indoors and nowhere for them to go with the windows closed.

The term "building ecology" has been coined to describe the interaction between building environments and their occupants (Levin, 1981). A healthy building is one that does not adversely affect the health of its occupants or the larger environment and an integral factor in this interaction is the indoor air quality of a building or home.

Many studies have shown that indoor air quality can often be several times worse than the worst outdoor pollution (apart from sandstorms!) and poor indoor air quality can substantially reduce health of families and reduce the productivity and general health and immune system function of workers in the office environment.

Problem causing emissions can come from outside in the form of car, truck or industrial pollution or be generated indoors directly from appliances, décor (such as adhesives, paints, lacquers, vinyl fabrics and flooring, carpets etc.) building products (such as particleboard, medium density fibreboard -MDF), cleaning products and furniture and fixtures (that contain foams, padding, vinyl fabrics etc) and contain enormous amounts of potential polluting substances that emit volatile organic compounds or VOCs.

These compounds evaporate out of the materials at room temperature and can cause a range of serious health impacts ranging from irritation of eyes, nose and skin, headaches, fatigue, poor concentration or ability to think clearly, difficulty breathing and nausea to long term impacts such as liver and kidney disease, cancer (IARC) and so on with studies showing 5% to 40% of office workers have been affected, depending on the symptom (Fisk, 1997, 2000). So it is very important to ensure the internal air quality of all buildings is healthy and clean.

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Figure 1: DV1 Air Ioniser for air purification
Image courtesy of Kempe (Aust)

While the best form of mitigation is avoidance, i.e. eliminating materials and products that emit VOCs from the home or workplace in the beginning, there are ways to clean up the air to make it healthy again. There are mechanical means such as air ionisers that produces negatively-charged ions which can assist in reducing airborne and surface borne contaminants and improving bodily function. These negative ion generators come at various scales for commercial use (such as DV1 illustrated in Figure 1) or residential/personal use such as Elanra, among the only ionisers globally to be officially recognised by government authorities as a Therapeutic Device, Elanra (shown in Figure 2 left to right as suitable for large room, small room/personal or individual), is registered in Australia by the Therapeutic Goods Administration, it is unique in generating small air ions. Small air ions are, compared to the medium and large sizes that in effect largely only clean air and surrounding surfaces, are medically active because they can be directly ingested by inhalation and pass through directly into the blood stream where they actively promote a variety of health benefits including:

  • Better sleep
  • Easier breathing
  • Faster recovery from illness
  • Less severity and frequency of colds and flu
  • Enhanced oxygen intake
  • Increased energy
  • Better concentration and learning
  • Stress relief
  • Improved vascular system
  • Removal of airborne pollutants including passive smoke
  • General health and wellbeing
  • Immune system recovery
  • Reduction in Allergy and eczema
  • Assisting with Chronic fatigue


Figure 2: Elanra Ionisers -left to right Mark I, Mark II and Pendant, office, room and personal ionisers -Australian TGA Approved
Image courtesy of www.negativeions.com

dracaena marginate.pngDracaena marginate
Image courtesy of Lechusa Planters

One can also take a more natural approach, it is possible to clean up air by introducing plant-based ecosystems into your indoor spaces. Before you discount this as sounding to complex or difficult, realize that it is as simple as bring pot-plants into spaces and keeping the soil and plants healthy,

Worldwide experience has recently been confirmed in Australia by research at the University of Technology, Sydney (UTS) that green plants are an effective way of reducing VOCs in internal air.

The indoor foliage plant species:

  • Kentia Palm (Howea forsteriana),
  • Peace Lily (Spathiphyllum 'Petite'),
  • "Janet Craig' (Dracaena deremensis),
  • Devil's Ivy (Epipremnum aureum),
  • Queensland Umbrella Tree (Schefflera actinophylla,)
  • "Amate' Spathiphyllum 'Sensation', 'Petite' and
  • Dracaena marginate

were all tested for their ability to remove VOCs from the indoor air. All seven plant types studied demonstrated benzene removal activity at similar rates. Kentia Palms were found to remove benzene up to 90% from a closed room after 24 hours. When ventilation was added to a room with a Spathiphyllum 'Petite' inside, the rate of benzene removal was improved up to 15%.

petite plant.pngStudies in Norway and the Netherlands have shown that health complaints at work can be significantly reduced by the presence of plants. Whether these effects are physical or psychological (or a combination of the two) is uncertain. What is clear, though, is that symptoms associated with Sick Building Syndrome (SBS) can be dramatically reduced by the addition of good plant displays.

Spathiphyllum 'Petite' in a sub-irrigated planter
Image courtesy of Lechusa Planters

Keeping plants healthy is very important to achieve this effect and the best way to achieve this is with planters that have sub-irrigation that reduces the frequency that plants need to be watered and introduces the potential for water savings. The water is fed into a tube from the top runs down and collects at the bottom of the planter, and is wick-fed through holes in the sub-irrigation base. Effectively, water use is determined as the plant requires, and there is reduced evaporation loss. A water level indicator is also generally included to indicate water supply.

Another effective plant based air improvement technique has been shown to be the "Green Wall". In this system, air is drawn through a porous wall kept constantly wet and covered with mosses and ferns, removing low levels of indoor air pollutants. Examples of green walls are shown here at the New T3 Terminal in Singapore and the Qantas Club Lounge in Sydney International Airport.


Integrating plants into the office environment has proven to be an effective, inexpensive, flexible and aesthetically pleasing biofiltration system that is self-sustaining as long as the plants are maintained adequately. Not only do they improve the atmosphere of any indoor environment, they help improve productivity, health and overall wellbeing of employees or your family.

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Elanra Ionisers: www.negativeions.com

DV1 Ionisers: http://www.kempeaustralia.com/dv1/

IARC: AGENTS REVIEWED BY THE IARC MONOGRAPHS, Volumes 1-88, International Agency for Research into Cancer, 2006



B. C. WolvertonHow to Grow Fresh Air: 50 Houseplants That Purify Your Home or Office


All websites last accessed on 9/4/13.