ONLY days after the state election Hobart was covered in a pall of smoke from a forestry burn-off.
Likewise days before the election the Australian Medical Association (AMA) and the Lung Foundation of Australia released its position statement on the Tamar Pulp Mill — this time much of Tasmania, including Hobart CBD, was engulfed in smog from both local and mainland bushfires. Apart from the remarkable irony, the smokey haze was a very tangible reminder of the politics and science of attributing the sources of diffuse pollution.
Whilst the AMA stated that any pulp mill would need to meet air quality criteria, the Minister, Mr. Green (interviewed on ABC TV) appeared not to be overly concerned. Perhaps this is because the enormous gaps in air pollution data, and the present inappropriate methods of measurement in Tasmania, means that it is generally possible to drive a [log] truck through any argument about the likely source and consequences of air pollution. Hence without appropriate baseline data, any impact assessment must be based on modelling — and assumptions. In the absence of an independent and professional State Environmental Protection Agency (EPA), Tasmanians may be subject to the spin and spiv of erroneous data.
How bad is air pollution in Tasmania?
Most Australians are aware that the purest air in the world can be found on the northwest coast of Tasmania (Cape Grim) as the roaring 40s bring pristine air to our western coast. However, what happens to this body of air as moves across the State is a different story. There are few places in Australia which have air quality as poor as the City of Launceston (located in the same air shed as the proposed pulp mill). In 1999 Sydney and Melbourne had a combined average of 1.5 days where air quality was in excess of the National Environmental Protection Measures (NEPM) value of 50 μg/m3 for P10 particles. Launceston (with about1/70th the population of Sydney) had 41 days. This measure has since improved in Launceston with a decline to 10 days in excess of the NEPM standard (but still notably high on a national scale).
Whilst the scale of problem in Launceston is well known, the sources of pollution remain a contentious issue. Domestic wood heaters and the natural inversion layer of the Tamar Valley clearly contribute to the problem. However little if anything is mentioned of the contribution made by both industry and forestry/agricultural burning. In late 2005, Launceston City Council was besieged by a [another] spate of internal brawling as alderman argued about the source of the city’s air pollution. A number of imaginative theories were proposed including the exhaust of aircraft travelling over the city (the 9/11 theory). Regardless of the bizarre theories, the most damning aspect of this debate was the fact that, after decades of knowledge of the extent of the problem, the city elders are still deeply divided about the source of the problem. Clearly the lack of a cause-effect relationship has not prevented a multi-million dollar campaign to reduce domestic wood heaters.
In contrast Hobart has markedly better air quality than Launceston — and this may continue to improve. However the improvement is unlikely to be associated with any real gains in air quality; it will more likely be associated with a decision by DPIWE to move the air monitoring station from its current location near the Zinfex smelter to a “more representative” location.
Bucket chemistry
The debate amongst the LCC alderman was triggered by statements made in the Draft Tasmanian Air Quality Strategy 2005 — a 120 page document authored by DPIWE. The document used data from the National Pollution Inventory (NPI) to “calculate” the amazing statistic that 73% of air pollution in Launceston is attributable to domestic wood heaters and open fires. This figure remains trumpeted across the LCC Air Quality webpage with the equally amazing prefix of “research has shown …” Unfortunately both the LCC and the media have chosen not to read the fine print.
The Draft Tasmanian Air Quality Strategy 2005 also contains a cautionary note which has been overlooked by all and sundry — “… The National Pollution Inventory (NPI) provides an estimate of the relative sources of PM10, however the data must be used with care”… What the report is alluding to is the fact that these data are not directly measured, but are estimated from the NPI database. Indeed the report does not describe how the NPI works — large industries who produce certain pollutants above a scheduled value must self-report an estimate of these pollutants to the Federal Government [that’s right — industry self reporting!]. Smaller industries who claim to be beneath the threshold do not have to report. Local Governments are required to provide an estimate of domestic and other pollutants. In the case of Launceston, the estimates for domestic pollution were weighted in the Draft Tasmanian Air Quality Strategy 2005 such that domestic woodheaters were arbitrarily ascribed with 100% pollution output whereas forestry burn-offs were only ascribed with 25% output. Rather strange!
To make matters worse, aggregated emissions (non-industrial) have not been estimated since 1998 and reporting is by municipalities (as we all know that air pollution is constrained by city boundaries). Whilst the CSIRO Atmospheric Division has conducted a number of studies into Launceston’s air pollution, none of these studies have been speciation (source) based — domestic wood smoke contributions have been assumed from mass balance modelling. In summary, the oft quoted “fact” that air pollution in Launceston can be mainly ascribed to domestic woodheaters seems to be based on an honesty system of self-reporting by heavy industries and ad-hoc and out-dated guess-a-metrics by city councils — with a twist of skewed weighting. No direct physical measurement of pollution source is involved!
Can the source of air pollution be determined?
The lack of measured air pollution source data in Tasmania is not because the technology is lacking. Indeed the science of air pollution speciation and measurement is well established. The Canadian EPA-equivalent (Environment Canada) utilises a large array of both mobile and fixed laboratory equipment to undertake Elemental Composition (EC) and Tracer Composition source studies (Brauer, 2005). Common methods include Proton Transfer Reaction Mass Spectroscopy (PTR-MS) to measure the volatile organic carbon content of air pollution.
In addition to this, it is also a relatively simple matter to measure the chemical composition of air pollution using Infra-Red Laser Spectroscopy and the responding data are defined by chemical species which are produced by individual industrial and agricultural processes. Smoke produced by forestry burn-offs produces a complex mixture of chemicals (including carcinogenic Polynuclear Aromatic Hydrocarbons — PAHs and Aldehydes) and a group of other biomarkers which are not found in smoke produced by a contained fire (eg. domestic wood heater). It is therefore possible to “fingerprint” smoke and determine its origin by its spectral characteristics. Infra Red Laser methods are also used to monitor forestry smoke by Canadian authorities. Measurement of Air Pollution from Satellites (MAPS) is a system which allows remote spectral analysis of smoke from any part of the world. So yes — it is possible to differentiate smoke produced by industrial, agricultural/forestry emissions from smoke produced by domestic woodheaters. Are these simple technologies used by Tasmanian authorities — seemingly not.
In Tasmania air pollution is only measured by Nephelometres. These devices are used to measure the distribution of particulate matter — that is they can tell how much particulate matter of certain size is in the air — but do not have the EC capacities to differentiate origin. More importantly, Nephelomtres presently used in Tasmania only measure particles of a diameter between 10 and 25 microns (P10-P25). As most respiratory medical specialists know, the most damaging particles in air pollution are of 2.5 micron diameter or less (P2.5). Almost 90% of Pulmonary and Tracheo Bronchial deposition occurs where particle size is less than 10 microns (Vedal, 2005). One must question what epidemiological useful data (if any) is presently collected in Tasmania for air pollution.
What are the sources of air pollution?
Parts of Canada (British Columbia — Toronto and Vancouver) share interesting parallels with Tasmania. The cities of Vancouver and Toronto are set in cool temperature valleys with inversion layers. Domestic heating in these cities is dominated by wood heaters and major local industries includes forest harvesting, timber and pulp milling. Many parts of British Columbia are also affected by forest fires (both natural and regeneration burns). All sound familiar?
As with Tasmania, the main culprit for air pollution in British Columbia was commonly thought to be domestic wood heaters. With the advent of chemical speciation studies, the picture has now somewhat altered in Canada. Whilst domestic wood heaters clearly are a problem (as in Tassie), speciation studies have pointed the finger towards other major sources of air pollution. Vehicle exhaust, road dust, agricultural burning and industrial process are now recognised as highly significant sources of air pollution in Canada. In Barnaby (Toronto) speciation studies have shown that up to 63% of air pollution is not locally produced and that the amount of Lead and Arsenic in P2.5 (produced by smelters) is equivalent in volume to the amount of Barium produced by woodsmoke (Brook, 2005). In a similar study conducted in the Utah Valley (Pope, 1989) there was 2-3 fold decrease in hospital admissions for children (respiratory disease) when the local steel mill was temporarily closed for maintenance. In the heavily industrialised port of Prince George, the local pulp mill was identified as one of the many contributing sources of air pollution (Noullett & Jackson, 2005). On the other side of the globe, an interesting study of air pollution in Dublin (Ireland) published in The Lancet demonstrated a decline in mortality associated with the banning of coal (mainly used in industrial boilers) in 1990 (Clancy et al., 2002). This study noted a 15.5% decline in respiratory disease deaths and 10.3% decline in cardiovascular disease deaths.
Lifting the smoke screen
Most people will agree that the crackdown on domestic wood heaters in Tasmania is justifiable and has been great initiative. However the media concentration on this source of air pollution alone has created the convenient “urban myth” that all air pollution problems in Tasmania are largely due to domestic wood heaters. Until we learn from the experiences of other countries and institute rigorous chemical monitoring (speciation studies) of air pollution — preferably by an independent EPA — we are unlikely to make significant in roads into improving our air. Governments need to recognise that industries, forestry and agriculture can be significant sources of air pollution and need to held accountable in the same way that ordinary citizens are.
Picture: A pall of smoke from forestry burnoff crosses Mt Wellington and descends on the suburbs of Hobart three days after the election. (Tuesday 21 March 2006, 6.30pm).
Cephissus Dry: When she is not busy being a professional goddess, Ceph enjoys the occasional pint of Creme de Menthe whilst indulging in a bit of statistical data analysis for the purpose of dispelling urban myths. Ceph is under the impression that science is often “managed” or manipulated by the forces of naughtiness. She also collects early Victorian tea strainers.
