Air pollution and its health impacts: the changing panorama

To the Editor: A recent MJA article by Kjellstrom et al1 correctly lists home heating using wood as a major cause of air pollution in Australia. It is therefore surprising to read in their optimistic view of "Circa 2100" that, whereas coal will be burnt in superefficient and clean-burning electric power stations, more wood will be burnt to heat houses.

When the Irish government banned the sale of coal in Dublin, there were substantial decreases in smoke pollution and mortality from respiratory and cardiovascular causes.2 If any evidence is needed that similar benefits can be expected from banning domestic wood heaters, it is to be found in recent research on the emission of fine particles and a wide range of toxic compounds by wood heaters, old and modern.3

The reason given by Kjellstrom et al for regarding wood-burning for home heating as desirable is that it would cause less global warming. But this reason is not convincing, as the potential "benefit" would be outweighed by the immediate harm inflicted by wood smoke on public health. People are unlikely to agree that we have to accept death and disease now in order to save the planet a few decades hence.

It is commonly claimed that the burning of wood is "greenhouse-neutral". This is not true if the burning takes place in home heaters, which emit methane and soot particles — both powerful greenhouse agents. When global emission rates and global warming potentials are both taken into account, the probable ranking of the three most important greenhouse agents is (first) carbon dioxide, (second) soot particles, and (third) methane.4 As almost everything in greenhouse science is fraught with high uncertainty, it is not possible to say what percentage of the potential greenhouse advantage of wood heaters is cancelled by their emission of soot particles and methane.

What can be said is that firing superefficient and clean-burning electric power stations with plantation timber is the best way to burn wood, using the greenhouse advantage without the toxic hazard.