Air cleaning devices

Air cleaning devices are available in Australia, especially as stand-alone devices for rooms, and are often marketed with little evidence to support their effectiveness. Such devices need to be able to demonstrate two key factors:

• That they can remove a range of pollutants from air, both gaseous and particulate, with a level of efficiency that is known and maintained over time.
• That they actually treat a sufficiently large volume of room air to cause a significant reduction in pollutant levels. For example, a high-efficiency device will need to treat more than four room volumes per hour if it is to reduce pollutant levels to about 20 per cent.

Gas heaters

Manufacturers of unflued gas heaters have been reducing nitrogen dioxide emissions for several years, producing ‘low-nitrogen oxides’ heaters for the Australian market. However, even these heaters will lead to nitrogen dioxide concentrations in buildings which are above health-based air-quality guidelines under circumstances where:

• the building ventilation rate is low, or
• the heating capacity of the heater is high relative to the building volume.

Additionally, some of these ‘low-nitrogen oxides’ heaters have been found to emit formaldehyde as a product of inefficient gas combustion.

Building materials

Wood-based panels use several types of resin in their manufacture which can emit formaldehyde gas for years after manufacture. Homeowners should consider keeping several windows open for the first six months after construction or renovation to counter the emissions of formaldehyde and VOCs from new materials.

Many countries now specify VOC emission limits for building materials and contents resulting in the availability of several hundred low-VOC products. However, this strategy has yet to be instigated by Australian industry.

Content Updated March 2005