Air Purification

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As the world becomes increasingly mechanised, more pollutants are being introduced into the environment. These pollutants are harmful to the health of the people and people are becoming more prone to respiratory problems like asthma. In Singapore, 20% of the children suffer from asthma problems. Air purifiers are introduced to filter and clean the air. However, these air purifiers might not actually reduce the toxicity of the air but in fact, some of them raise indoor ozone concentrations to above safety levels.

Greenology offers a better alternative by cleaning the air biologically using plants. Other than removing carbon dioxide by photosynthesis, they convert toxic chemicals into less harmful by-products and sequestering heavy metals.

According to research undertaken by the National Aeronautics and Space Administration (NASA), leaves of indoor plants are capable of removing formaldehyde, which is produced by many household products, and carbon monoxide. VOCs, TCE, benzene, toluene, xylene etc. can be removed by the roots of the plants, or be degraded and removed by microorganisms living near the roots of plants.

The table below shows the common toxins found in our indoor environment, their harmful effects and the green wall plants which are able to remove these toxins as shown by research and studies.


Toxins Found in/ produced by Harmful effects Can be removed by
Benzene Gasoline, pains, plastics, rubbers, inks Low exposure:

Irritate skin and eyes


High exposure:

Headaches, loss of appetite, drowsiness, nervousness, psychological disturbances

Trichloroethylene Dry-cleaning, inks, paints, varnishes and adhesives. Liver carcinogen




Formaldehyde Consumer paper products, common household cleaning agents Low exposure:

Irritates eyes, nose and throat.


High exposure:

Irritates upper respiratory tract, headaches, asthma

Boston Fern

English ivy (Hedera Helix)


VOCs (Volatile Organic Compounds) Petroleum products, flooring adhesives, paint, furniture, wall materials, electronic equipment etc. Primary precursor to formation of ground level ozone and particulate matter in the atmosphere Scindapsus



Carbon Monoxide Gas stoves, appliances, heaters, vehicle exhausts Low exposure:

Dizziness and headaches


High exposure:







  • Claudio, L. (2011). Planting Healthier Indoor Air.Environ Health Perspect Environmental Health Perspectives.