Wood vs other forms of heating

The bar chart, based on a leaflet from the Puget Sound Air Pollution control agency compares particulate emissions from various forms of home heating. US EPA certified heaters produce similar amounts of pollution to heaters satisfying the latest Australian standard. This means 10 houses heated with correctly operated certified woodstoves produce as much pollution as 4,000 houses heated with natural gas.

The Australian standard for particulate emission from woodstoves (AS4013) is for a maximum of 5.5 g / kg of wood burned, averaged over the complete burn cycle. At a density of 500 houses per square km (2,000 square metres per house), each house burning 1 kg per hour, 13750 grams of particulates would be produced in 5 hours. If not dispersed but spread over the square km to a height of 10 m, the PM2.5 concentration would be 1375 micrograms per cubic metre. The proposed Australian Federal Air Quality standard is 50 micrograms (mcg) per cubic metre. Sydney averages about 11 mcg/m3. It is, of course, difficult in general to predict how the particulates will be dispersed in the air, under different weather conditions.

Unfortunately in Armidale, the local meteorological conditions - typically clear, still nights, with inversions - and the local topography - a shallow basin-shaped valley - combine to produce high concentrations of smoke on many nights during winter. For example, in June 1997, in 11 out of the 22 nights measured, the air pollution index for East Armidale was in the extreme category.
 
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