Australia State of the Environment Report 2001 (Theme Report)
Lead Author: Dr Peter Manins, Environmental Consulting and Research Unit, CSIRO Atmospheric Research, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06746 9
Regional Air Quality (continued)
Haze across regional airsheds [A Indicator 4.12]
Measurements of light scattering indicate the prevalence of haze. Cloud and fog contribute to haze, but since the monitoring instrument (usually, a nephelometer) heats the air before it is measured, these are not accounted for. Results are usually presented in terms of local visual distance (LVD). A goal of at least 20 km for LVD is, for example, operating in Victoria, Western Australia and Queensland, and 9 km in New South Wales.
Available data for regional areas of Australia (Figure 158) show that haze is a very variable occurrence. There is no trend evident in the number of days during which haze is present, except a strong increase in Mackay, but that may just be a result of the short record. There may be a relationship with bushfires and burning off in dry years, but the evidence is yet to be presented.
In one regional centre, Armidale, monitoring data through the winters of 1997 and 1999 showed many days when LVD was below 2 km for several hours at a time (Armidale 2000). The use of wood heaters was thought to be responsible.
Figure 158: Number of days when local visual distance was below 20 km as determined by a nephelometer.
Negative values represent zero exceedences.
Source: data from EPAs and EPAV (1990)
There is much evidence of a strong relationship between haze and fires in rural and regional Australia. A major cause of haze in southern latitudes is winter wood heater smoke. In other seasons and locations, smoke from fuel reduction burning or bushfires is implicated. There also may be a contribution from urban emissions leading to downwind photochemical smog and haze.
Improvement in haze levels will require improvement in fire management, whether that be fire for fuel reduction or for domestic heating.