Image for Air pollution and woodsmoke

Air pollution and woodsmoke are controversial subjects.  A CSIRO study, partly funded by Forestry Tasmania, found that in Geeveston, a Huon Valley town with 277 houses, 77% of pollution was from wood heaters and 11% from forestry burns.

Forestry burns emit a lot more total pollution (8,900 tonnes per year compared to 120 tonnes for wood heaters), but a large proportion rises into the atmosphere and disperses.  By contrast, wood heater smoke is often trapped by cold air in the valleys, so it infiltrates houses where people live and spend time with their families.

An important research project, published in 2007, compared death rates in Christchurch, NZ with air pollution (76% of which comes from wood heaters).  Compared to the cleanest areas of the city, the smokiest areas had:

• 68% more respiratory deaths

• 22% more in circulatory deaths

• 16% more deaths overall

This research clearly shows that woodsmoke is bad for our health.  The increased death rate from woodsmoke is almost identical to the increases expected from exposure to similar amounts of traffic pollution, or passive smoking.

Although the health effects are similar, the amounts differ. A typical Australian wood heater emits more health-hazardous PM2.5 pollution in one day than the average passenger car emits in a year.  This explains why Geeveston, with just 277 houses, exceeded the PM2.5 air quality standard 99 times in 20 months, but Sydney, a massive metropolitan, has few exceedances and just over half Geeveston’s annual average measured PM2.5 pollution.

PM2.5 stands for particulate matter less than 2.5 microns (millionths of a metre).  PM2.5 are so small they penetrate the deepest recesses of our lungs, where they cause inflammation leading to heart and lung diseases, as well as cancers.  Now considered the most health-hazardous air pollutant, PM2.5 cause about 20 times as many premature deaths as the next worst pollutant (ozone).  There is no known safe level of PM2.5, below which adverse health effects have not been found.

Even though smoke is discharged outside houses, PM2.5 are so small they behave like gases.  The only way to keep them out is to make houses airtight, but then we’d die from lack of oxygen.  In 2003, homes in Launceston had higher PM2.5 over the entire winter from woodsmoke entering from outside, than if a 1-pack per day smoker lived in them.

Woodsmoke contains the same and similar chemicals as cigarette smoke, and is associated with the same health problems - heart and lung diseases, middle ear infections, bronchiolitis, increased risk of colds and flu, with the latest research showing that toxic chemicals known as PAH, found in both wood and cigarette smoke, also cause genetic damage in babies and reduced IQ of children starting school.

When residents of Christchurch realised what woodsmoke was doing to their health, and that previous efforts, e.g. setting a new emissions standard in 2000 equal to a quarter of what Australia currently permits, had failed, regulations changed.  Wood heaters are not allowed in new houses, or houses that don’t already have them.  The Clean Heat program replaced 1,973 woodheaters with insulation and reverse cycle airconditioners.  This helped reduce pollution. 

Follow-up evaluations showed that the new, efficient home heating system increased electricity use by only 1% (perhaps residents occasionally used supplementary electric heat in other rooms).  So the increased electric bills were a tiny fraction of the cost of buying firewood – families had warmer houses and saved money. 

Southern California also calculated the cost of woodsmoke pollution and no longer permits wood heaters in new houses. Even Montreal, with average daily maxima of minus five degrees centigrade, considered the health costs, banned the installation of new wood heaters, and has just announced $6 million funding to remove existing one.

These initiatives follow advice from the American Lung Association and the Australian Lung Foundation not to use wood heating when alternatives are available.  Similar recommendations were made in July 2011 by a team of 50 scientists from the United Nations Environment Program and the World Meteorological Organization.  The scientists recommend phasing out wood burning stoves in developed countries to reduce the risk of catastrophic climate change, as well as to improve health.

Should Geeveston follow this advice?  As in Christchurch, residents could consider insulation and the efficient reverse cycle systems that increased electricity use only 1%.  They could also consider local wood-fired power generation, or perhaps combined heat and power system that could create affordable, environmentally-friendly heat.  Perhaps Federal funding, a key component of Launceston’s woodsmoke reduction program, might be available. 

Or perhaps Forestry Tasmania could fund a pilot project to assess the feasibility of reducing the amount of wood burned as waste?  The 50-scientist UN report also recommended phasing out agricultural burns!

Parents often go out of their way to protect children from cigarette smoke, so caring parents should be concerned enough to avoid the much higher levels of toxins in woodsmoke.  The cost of non-polluting heating pales into insignificance compared with genetic damage to babies, or the potential loss of income from a 5 point reduction in IQ from exposure to more than 2.26 ng/m3 of PAH, a tiny fraction of measured PAH in areas affected by woodsmoke.

Just as we removed lead in petrol to protect our children’s health, people are starting to recognise the need to remove current woodheaters, each of which emits more PM2.5 pollution per year than several hundred passenger cars.  Less-polluting cars that use lead-free petrol were developed, so perhaps we could develop new wood heaters that are no more polluting than the average car. By identifying these, or other affordable alternatives, we will all enjoy better health and cause less global warming, creating a healthier, safer environment for future generations.

Dr Dorothy L Robinson, Australian Air Quality Group, http://woodsmoke.3sc.net/