[Stoves] Between PM 2.5 and PM 10

[Crispin Pemberton-Pigott]

Dear Jay

 

I appreciate the discussion. I have been working with Prof Lodoysamba in
Mongolia for going on 6 years with a view to burning  (rather than emitting)
the vast majority of particulates produce by the evaporation of lignite in
domestic stoves. The (nuclear methods) analysis of the component particles
by Lodoysamba and a university in New Zealand has been particularly
instructive in that the chemical composition of the particles allows for a
source apportionment to be constructed and the influence of a stove
replacement programme (ongoing) to be evaluated.

 

With this in mind, the composition of the smoke from cigarettes and coal and
wood is probably worth thinking about because I believe they are not all
that similar. While obviously there are overlapping compounds such as
formaldehyde, CO and so one, the health risk is not from particle per se but
from what they contain, factored for their size (in the sense of being able
to deliver their 'payload'). This raises the question of how to compare PM
concentrations of PM2.5 that have very different source materials.

 

The comparison made using 'x number of cigarettes per day' is valid if we
speak only of particles, but are there not large differences between the
typical condensed tars from cigarettes and the hydrocarbons from lignite and
the BC or condensed volatiles from wood fires? It is unlikely they have
identical health impacts.

 

The reason I ask is that in order to assess the value of avoiding PM2.5
emissions, we have to create an impact assessment method. In Ulaanbaatar the
$ value of the health impact was made by Jostein Nygaard (WB) and we have a
target reduction - now to be >80% - whereas before it was not even
considered possible to achieve that. The difference is the application of
modern combustion principles to the stoves which has allowed us to achieve
reductions in excess of 98% relative to the (rather terrible) baseline.

 

When seeking funds we have to justify the expense and show value for money.
If I pull a 'equal to xx cigarettes' argument out of my back pocket, I have
to defend the direct comparison of PM mass concentrations between wood smoke
and tobacco smoke. I am not aware of that having been asserted and defended.
Because woods and coals vary considerably in content (i.e. Ulaanbaatar coal,
for example, being particularly low in Sulphur and tars) it would seem
necessary to do the sort of investigation that Lodoysamba has been
performing (best ref is the AMHIB Report, part of the UB-CAP chain of WB
activities).

 

What is your view?

 

Many thanks
Crispin

 

 

C Pemberton-Pigott

Senior Technical Advisor,

Stove Emissions and Efficiency Testing Laboratory, (SEET)

City of Ulaanbaatar

Mongolia

crispin at newdawn.sz <mailto:crispin at newdawn.sz>  

++++++++++

 

I'm traveling and don't have access to all my files as a result so I can't
give you details from when I was actively working on this a few years ago.
There is only 1 study that I could find then that modeled the passive
particulates in a house from a certain number of cigarettes being smoked and
a typical amount of air exchange.  The levels were actually around the lower
part of the range in the group in Guatemala that had the rocket stoves
installed.  For cigarette smoke,  we know that this amount of smoking in a
household is associated with increased childhood pneumonia.  In the
long-run, personal exposure is what counts and this is hard to measure for
particulates which is why Kirk Smith's group used personal CO monitors on
children instead.  I think it would be useful for someone to mount a large
study that paid women to carry a particulate sampling system inside a
life-size baby doll to get accurate ranges for what a typical infant is
exposed to.  Ideally this would be done in multiple locations where
etiologic research on pneumonia in children is being done.  Unfortunately
the clinicians doing those large studies did not opt to look at smoke
exposure levels; that probably goes along with the mindset that has been
encountered in the past from the Gates Foundation that seems to dismiss
attempts to lower exposure to combustion products as not as worthy of
attention as their efforts to diagnose and treat these pneumonias more
quickly and adequately in order to lower the death rate.

 

Jay Smith, MD, MPH

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