[Stoves] Day 2 Report on Day #1 (Saturday) of ETHOS conference

[Crispin Pemberton-Pigott]

Dear Andrew

I completely agree, and that is why there is rankling in the air quality
sector about claims made by stove promoters that all PM2.5 has the same
toxicity. I am speaking of the modelled health consequences of exposure to
particles, whether dry, liquid or gaseous. 

Everything from Plutonium to dentritic hydrocarbons to water droplets is
treated as 'PM2.5' with equal toxicity.  You can imagine how this goes down
with the professionals.

It is obvious that when it comes to PAH in food, smoked fish for example,
there are several sets of substances: PAH4, PAH7 (USA), PAH8 (EU), PAH16
(USA) and PAH 20 (EU). There are sets of PAH's that are deemed really
carcinogenic and ones that are not as bad.  Food is tested for sets and must
meet various limits depending on the class of toxin it is.  PAH7 (or 8) is
deemed really bad where the rest that make up PAH16 are in a different
category.  We can't just say "PAH". That is like saying "wood" to describe
biomass.

Similarly, PM2.5 could be silica dust from the ground or condensed water
vapour or condensed creosote or vinegar from boiled wood sap, or CxHy from
smouldering coal or a lousy kerosene lantern.  

PM2.5 is a very useful, but nevertheless, blunt tool. In future we will have
to do more of the kind of work Prof Philip Lloyd has been doing in Cape Town
with VOC and PAH measurements. We are so lucky to have talented chemists in
the stove community.

Regards
Crispin

+++++++
>Fan stoves I have tested all have significant (meaning clearly detectable)
PM4.0 appear as soon as the fan is turned on (ash).  

I had a brief exchange with Tammy on this list some years back about the
higher velocities of fan assisted stoves lofting ash into the flue gases, at
the time my inference was that fly ash was a lesser evil than Particles of
Incomplete Combustion.

AJH