Posted by: Matthew | June 4, 2010

Averaging measured woodsmoke pollution levels masks some real problems.

The standards in New Zealand for how much particulate pollution is allowable are:

National standard and guideline values for PM10
Standard 50 μg/m3 24-hour mean with One 24-hour period exceedence per year.
Guideline 20 μg/m3 Annual

Then if it:

Exceeds guideline/standard it is completely unacceptable by national and
international standards.
Alert Between 66% and 100% of the guideline/standard
Acceptable Between 33% and 66% of the guideline/standard
Good Between 10% and 33% of the guideline/standard
Excellent Less than 10% of the guideline/standard

But those 24 hour measurements can hide some peaks. On page 8 of this pdf it can be seen that Masterton hit 180 micrograms at 9pm on July 14 2008, yet measured over 24 hours it was only 52 micrograms. Pity if you tried to breathe the outside air in Masterton that night. It would have been incredibly toxic and unbreathable.

And the annualised figures for the 20 micrograms over a whole year takes in summer when people who aren’t using their woodburners.

And what tests have actually been done? Is 10micrograms over a cubic metre unpleasant to be in? What about 15 micrograms? What about 50 micrograms? Has a wide study been done getting people’s reactions? What level of smoke triggers asthma attacks? Shouldn’t we have an allowable peak measurement, rather than annualise the data or average it over 24 hours?

And why aren’t their policies for dealing with excessive exceedences? It is easy to predict how much smoke there is as a function of temperature and windspeed. Why can’t we ban using woodburners on any night where there is going to be an exceedence?

And even then if we tightened up our standards, lowering the acceptable levels to be more like peoples’ real views on what constitutes acceptable to them, and acceptable to asthmatics, we’d still have to have a veto right over our neighbours simply because this picture is often true:

With all these desperately needed provisos on when people should and shouldn’t be allowed to operate their woodburners it could be seen to be very wise to just ban them outright. They certainly cause a lot of problems and ill-will that our community could do without.

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