Monday, February 20, 2012

An aside: wood smoke in Tas.

In the heat of summer, it's easy to forget the depths of winter. This story was in the news today:

Scientists from the University of Tasmania, the Menzies Research Institute as well as US and Canadian universities found smoke from forest, grass and agricultural fires affect the climate, air quality and human health... Report co-author David Bowman says there are implications for forestry burns in Tasmania."We are exposing populations to risks and preventative measures have got to be taken."... "There has got to be an understanding that people who complain about the smoke have a legitimate case, the medical science is on their side now," he said.

However the story, based on a report commissioned by Forestry Tasmania, deflects the reader's attention to other causes:

Last year a CSIRO study into air quality in the Huon Valley, south of Hobart, found woodheater smoke significantly outweighs emissions from forestry regeneration burns.

The reason, according to the study, is that hot regeneration burns create so much heat that convection currents carry the smoke high into the atmosphere. That's the theory but we have seen pictorial evidence that the smoke doesn't always rise very high and sometimes the smoke is blown elsewhere. Wood heater smoke stays low and is often trapped by layers of cold air. This next extract describes the major source of the wood smoke problem in cities and towns:

Wood heaters particle emissions are lowest when the heaters are burning efficiently – that is that you’ve got plenty of air supply to it – so the one thing that you don't really want to do with a wood heater is to shutdown the damper and stuff it full of fuel to keep it burning overnight.

This is why, for us, living in valley towns like Derby and Branxholm is out of the question. Thankfully our soon-to-be residence is right on the edge of Weldborough away from smokey chimneys on cold winter nights. I wonder if the locals could be re-educated to use heaters in the most efficient manner and to cut down on smoke emissions. After all, clean air is in everyone's best interests.


Anonymous said...

Yes, and their carbon traders. The epidemiology they use for cost benefits is made from selective data and they do not back it appropriately with relevant and specific data collected from toxicology studies. It's PR hype!

jrh001 said...

"In the Huon Valley smoke from smouldering heavy logs and stumps following yesterday’s burning became trapped in the overnight fog leading to elevated particle concentrations being measured at Judbury, Huonville and Geeveston between 7 AM and mid-day." from today's Forestry Tasmania media release.

jrh001 said...

From Forestry Tasmania today, High intensity burns "Two burns are west of Weldborough. Two are in the vicinity of Pyengana... The smoke from the burns in the north-east is expected to move away to the south at high elevation. Some residual smoke is expected to accumulate in low lying areas overnight if wind speeds do not increase as predicted."