Dusting off a myth
In the past, carpet has been unfairly singled out for its alleged association with dust and allergies. However those views are little more than urban myths.
For allergy and asthma suffers, the critical issue is the amount of dust and allergens present in the air they breathe.
A recent study by the German Asthma and Allergy Foundation (ALLERGIE konkret 2/2005) found that wall-to-wall carpet reduces dust in the air to half that found above hard flooring surfaces.
|Fine dust concentration||Particulates (µg/m3)|
|Fine dust concentration with hard floor covering||62.9|
|European Safe Limit Standard||50.0|
|Fine dust concentration with carpet floor covering||30.4|
(Ref: German Allergie and Asthma Bund, Media Release 18 June 2005)
The German study backs up the views of Australian respiratory experts Marks & Abramson in their paper ‘House dustmite avoidance: Facts and fiction’ (Asthma Update 2001). Reviewing evidence of the effectiveness of the various dustmite exposure minimisation strategies and clinical evidence, Marks & Abramson conclude that removing carpet has not been demonstrated to reduce overall dustmite allergen exposure in the home and recommend against any drastic and unproven lifestyle modifications such as removing carpet.
It has now been proven that a properly maintained carpet has a positive effect on Indoor Air Quality.
- Asthma Update June 2001 published by Australian Asthma (pdf, 1578kb)
- DAAB study – Summary (pdf, 417kb)
- DAAB study – Full Report (pdf, 344kb)
- Allergens in the home (pdf, 123kb)
Indoor air quality
Australians typically spend 90% of their time indoors – so indoor air quality is an important factor in protecting health and wellbeing.
The main factors that affect indoor air quality are:
- inadequate ventilation which may occur if heating, ventilating and air-conditioning systems (HVAC) are ineffective,
- chemical contaminants from inside and outside the building — these include volatile organic compounds (VOCs),
- biological contaminants e.g. bacteria, moulds, pollen.
Many countries have instituted standards and voluntary codes of practice that set guidelines for indoor air quality.
VOC emissions consist of a range of volatile organic compounds which at room temperature may be released from materials or products in the form of gases. Some of the common sources of VOCs in the indoor environment are cleaning agents and polishes, cosmetics and deodorants, dry cleaned clothing, building materials (e.g. adhesives, laminates, caulking compounds, medium density fibre board), furnishings (furniture, drapery and floor coverings), office equipment (e.g. photocopiers and laser printers), cigarette smoke and air drawn from outside.
Carpets and VOCs
As part of the manufacturing process, carpet is generally baked in a finishing oven at 150°C to 170°C. This drives off most of the volatile chemicals including solvents in adhesives and raw materials, leaving a product with a low remaining VOC content.
When compared to other building materials with significant indoor exposure, carpet is a minor contributor to VOC emissions. Approximately 90% of all VOCs discharged from carpet dissipate within 2 days of installation.
In addition, carpet has a purifying impact on indoor air quality by absorbing some toxic VOCs and trapping particulates present in indoor air. For example, carpets irreversibly remove VOCs, including the toxics formaldehyde, sulphur dioxide and nitric oxide.
Tips for installing new carpet:
- The area should be ventilated with fresh air during installation to avoid re-circulation of air. Most emissions dissipate quickly with adequate air exchange and ventilation.
- Vacuum the floor after the old carpet and underlay have been removed.
- Operate the ventilation system at the normal room temperature for 72 hours after installation. If possible open windows and doors to maximise fresh airflow.
- If carpet adhesives are used, ask for a low VOC emitting water-based adhesive.
- If you are sensitive to VOC emissions, leave the premises during and immediately after carpet installation.