Annual Australian PM2.5 emissions:
Woodsmoke 40,000 tonnes, mining 7,700 tonnes, electricity generation 12,000 tonnes.
Sources: woodsmoke, woodheater consultation RIS p2, April 2013; mining & electricity generation NPI 2011/12 data.
Woodheating is largest source of PM2.5 pollution in a mining & power generation town
Muswellbrook (population 11,791) is surrounded by open cut mines as well as two power stations that generate enough electricity for 3.25 million homes. In Sydney's mild climate only 5% of homes use wood as the main form of heating. Muswellbrook is slightly colder, so perhaps 10 to 20% of the 4,000 homes will have wood stoves. Yet these 400 to 800 wood stoves cause more pollution in winter than all other sources put together!!!
Fig 49 of the Upper Hunter Fine Particle Characterisation Study final report shows the sources of PM2.5 pollution in Muswellbrook Smoke from domestic wood-heaters is in yellow, smoke from wildfires and forestry burn-offs is shown in green. Smoke from domestic wood heaters represented 62% of Muswellbrook's PM2.5 pollution in winter and 30% over the entire year.
Upper Hunter Fine Particle Characterisation Study: Sources of PM2.5 pollution, Muswellbrook
The study focused on PM2.5, because they are "associated with greater health risks than coarser particle pollution...The evidence is clear that long-term exposure to PM2.5 has a larger health effect than short-term exposure, suggesting that strategies that provide long-term reductions in particulate pollution are likely to produce the greatest health benefit."
Fig 49 of the final report shows that, despite the mining, the air in Muswellbrook is no worse than Liverpool (see graphs, right hand column of this page), except possibly in winter when woodsmoke accounted for 62% of PM2.5 pollution. In contrast, only 38% of Singleton's PM2.5 winter pollution was due to woodsmoke, resulting in much cleaner air in winter.
Despite Muswellbrook's proximity to the Bayeswater power station (generating enough electricity to power 2 million average Australian homes) and the Liddell power station (enough to power 1.25 million homes), the largest single-source of PM2.5 particles collected on the filters at Muswellbrook was from wood heating, representing 30% of the year-round total. The second highest proportion was secondary sulphate particles (17%) followed by aged sea salt (13%), smoke from burn-offs and wildfires (12%) and soil (11%).
MUSWELLBROOK, Hunter Valley. The high proportion of PM2.5 from domestic woodheaters was reported 2 years earlier:
Media release: 28 June 2011:“The NSW Office of Environment and Heritage reports today that higher concentrations of PM2.5 particles measured at the Muswellbrook and Singleton air quality monitoring sites in the Upper Hunter over the weekend was likely due to woodheater use.”
The seasonal pattern of measurements of at Muswellbrook, from the start of monitoring in December 2010 shows peaks in winter most likely due to wood heaters, but a somewhat elevated background level from mining and possibly some hazard-reduction burns in spring. (PM2.5 data available for download from the NSW EPA)
Note that, as shown in the Google Maps photo below, Muswellbrook is surrounded by mines and is close to the
Bayeswater and Liddell power stations (which generate more than enough electricity to power all the homes in NSW).
Comparison: Armidale vs Muswellbrook. Although Muswellbrook's pollution seems quite high, rural towns where a higher proportion of households use wood heating have even higher pollutions, as shown by the comparison of PM2.5 levels in Muswellbrook and Armidale, NSW. On still, windless days wood smoke is not blown away (photos, right), resulting in double the PM2.5 pollution of coal towns such as Muswellbrook.
submission on the Federal Government's Consultation Regulation Impact Statement
Geeveston, a small town with
277 houses had 99 exceedences of the advisory PM2.5 standard in 20 months. A nearby rural area (the Department of
Primary Industry Research Station near Grove) was much cleaner. The graph below is from the CSIRO report,
which concluded that domestic wood heaters in Geeveston were responsible for
77% of anthropogenic PM pollution, compared to 11% from prescribed burns.
PM2.5 measurements from a study in Launceston, showing that woodsmoke builds up close to individual wood heaters, as well as in the bottom of valleys.PM2.5 values are represented by the symbol colour (red is 100 μg/m3 or more, green is near 50 μg/m3 , dark blue is near 10 μg/m3. This level of pollution was measured in an area where wood heater use was estimated to have dropped to 15% of households in 2010 ( woodheater consultation RIS p85). The many areas with PM2.5 measurements approaching 50 ug/m3 and many areas with measurements close to 100 ug/m3 suggests that residents living within 100 metres of even a single wood heater may be subject to elevated PM2.5 levels sufficient to damage their health.
Need to correct NPI data, or warn users that PM2.5 emissions from domestic wood heaters are ignored. Many people are confused by the fact that the National Pollutant Inventory does not report PM2.5 emissions from domestic wood heaters (the largest single source of PM2.5 in Muswellbrook, postcode 2333). By diverting attention away from the most cost-effective way of reducing exposure to PM2.5, the erroneous output from the NPI hinders attempts to reduce pollution and safeguard our health. Such an unsatisfactory state of affairs should be fixed as soon as possible, either by including emissions from domestic wood heaters, or at least by providing warning messages on the output that this major source of pollution has been ignored.
As shown below, the output gives no inkling that major sources of PM2.5 emissions are not included, so it totally confusing and misleading.
The American Heart Association explains: “Fine particulate matter (PM2.5) affects more people than any other pollutant, with chronic exposure causing the most deaths from serious disease”. An increase of 2 μg/m3 in PM2.5 exposure was associated with a 0.32% smaller total cerebral brain volume and a 46% higher risk of covert brain infarcts, a type of silent stroke. Despite its proximity to mines and power stations generating electricity for 3.25 million homes, CSIRO's chemical fingerprinting showed that 62% of PM2.5 in Muswellbrook in winter was from domestic wood heaters. People need impartial information to counter the widespread misunderstanding that the woodsmoke-polluted air they breathe has only a fraction of the PM2.5 pollution from coal and power station pollution in the Hunter Valley, when it fact woodsmoke is also the dominant pollutant in the air of Hunter Valley towns such as Muswellbrook.
Shouldn't tackling woodsmoke be a high priority? Emissions inventories and air pollution monitoring data indicate that smoke from woodheaters is a major source of fine particles and other air toxics in many parts of Australia including the Hunter. The recent Senate enquiry noted that tackling woodsmoke would achieve 66% of the benefits for just 1% of the costs of meeting air quality standards. Shouldn't addressing this preventable health issue be a No 1 priority?
How much reduction in particles is enough? Given the health damage caused by PM10 and PM 2.5s, is it satisfactory for our leaders to aim for only a small reduction to exposure, such as 10% or 20%? Should some sources of particles such as the burning of wood for heating/BBQs, be phased out altogether?
AAQG Comment: With domestic wood heaters now considered responsible for more than 50% of PM2.5 emissions in Sydney, and analyses showing that phasing out wood heaters when houses are sold in NSW would reduce health costs by $4,015 million for a cost of just $36 million (see Table 2, right hand column of this page) the real question is why is this not happening?
WHAT IS A SAFE DISTANCE TO LIVE FROM A WOOD HEATER IN AN URBAN AREA?
AAQG Comment: A typical Australian wood heater emits about 10 grams of PM2.5 per hour, and is often used on cold days and nights when temperature inversions trap the air close to the ground. In 2 hours, a source emitting 10 grams per hour is enough to generate PM2.5 concentrations of 50 ug/m3 over an area area 200 metres x 200 metres to a height of 10 metres. This suggests that it would be unwise to live within 200 metres of a house using a slow combustion wood heater as the main source of heating, especially if the prevailing wind blows the pollution in your direction.
How does the air in Newcastle and the Hunter compare with Sydney or cities overseas?
The graphs below compare PM2.5 measurements Singleton and Muswellbrook (downloaded from the NSW EPA website) with ANSTO's PM2.5 measurements for Liverpool, Sydney. Liverpool's pollution increases in winter because of wood heater use. Singleton has lower wood heater emissions, and lower PM2.5 averages in most months than Liverpool. In contrast, Muswellbrook has cleaner air than Liverpool only from December to April. Its PM2.5 pollution is worse than Liverpool from May to August because of wood heater use, and from September to November, biomass smoke from bushfires and burn-offs may have contributed to the slightly higher PM2.5 measurements at Muswellbrook, compared to Liverpool.
A study in Tasmania, (where wood heaters are the dominant form of PM2.5 pollution) investigated the relationship between accurate PM2.5, measured using the the low volume air sampler (LVAS) and TEOM readings. True PM2.5 were found to equal to 1.79 * TEOM_PM2.5 - 1.2. This a wintertime TEOM reading of 10 is equivalent to a true PM2.5 concentration of about 17 ug/m3 - our air quality may not be as good as previously thought.
CANBERRA. ABS data on main source of energy for heating 2011 (click to enlarge) - wood heaters used as the main form of heating by 2.3% of ACT residents, yet there is a substantial increase in PM2.5 pollution in winter, consistent with a substantial increase in pollution when residents start to use wood heating.
In SYDNEY, only a small proportion of households in Sydney use wood heaters, but analyses of PM2.5 particles collected on filters in Liverpool show that almost half of those in winter come from domestic wood heaters. The research publication, Cohen et al. – Atmospheric Pollution Research 2 (2011) 182‐189, notes that “Clearly wood heaters in the Liverpool area in winter are a major source of fine particle pollution.”
A study of air pollution and health concluded in 2006 that fine particle pollution was contributing to the premature deaths of up to 1,400 Sydneysiders every year. The NSW EPA graph of health-hazardous PM2.5 emissions in the Sydney region, derived from the emissions inventory for 2008, makes it is only too clear, everyone who cares about their health should demand immediate action to implement the 3 effective woodsmoke-control measures and save $6 billion in health costs.