[Stoves] Malawi Philips stove intervention study and Nikhil's 28 sins of insolence about GACC/WHO (Re: Ron Larson)

[Andrew Heggie]

[Default] On Thu, 19 Jan 2017 00:02:53 +0000,Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:

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>A GBD is a post-death analysis and attribution of what contributed to the deaths of the total population of dead people. No individual was examined to create the attribution, it is a 'population statistic'. When they say all people who died prematurely (pick a number) did so from a variety of contributing causes. They are listed, and the % contribution to the pre-mortality is listed in a table.

Lay people read this list so it's best to keep jargon to a minimum, in
this modern electronic age is there any point in resorting to
abbreviations, in the past the expanded text would have been used at
the first occurrence and then the abbreviation subsequently.

I had gathered that was what Nikhil was saying and it was also pointed
out the causal link between tobacco smoking and  lung cancer took a
long time to establish yet the attribution was made much earlier (i.e.
smokers were dying of lung cancer in greater numbers than non
smokers).
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>It does not mean that anyone in particular died from exactly that combination of contributing causes. They are just attributed. Therefore removing the attributed cause entirely from the current population may have no effect at all on the current population for two reasons: first there may not have been a correct attribution in the first place, and second, we have no idea what the total disease load on the person affected by this intervention will be in future, and how other confounding factors will manifest themselves.

Again I see this, it doesn't swerve me from the belief that avoiding
breathing in smoke is sensible.
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>In short, you can’t use a guess about what happened to an entire population in the past to claim something about a particular person in the future. Yet that is exactly what is being advanced by this particular set of emission targets for cooking stoves.
<snipped>

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>The Malawi study may not have proven anything for or against the argument. It was in a sense, a search for ‘bespoke science’ – seeking proof for an assertion. Nothing wrong with that, but it is not a very helpful suggestion to say, as they did, that maybe the Philips stoves were not clean enough to demonstrate that solid fuels can burn well to reduce the incidence of pneumonia. That is not the appropriate counterfactual. It sounds more like, “We think solid fuels cannot burn cleanly enough to ‘meet WHO IAW guidelines’ and are trying to find a way to prove it.”

I did not take that from the study, I also think Nikhil was unfair on
those who did the study and my take was that they also concluded  the
stoves could only make an insignificant improvement to the daily
exposure to pollution from particulates because there were other
sources of exposure and pre existing health problems, mostly
attributable to extreme poverty.

Given that I, not a medical professional, had come to believe that
exposure to cooking smoke was linked to infant respiratory problems
and this was linked to premature deaths, I can at worse say that the
researchers were naive in expecting an improvement. It doesn't mean
the improvement is not worthwhile in other circumstances.

Of course some of the discussions on this list may have promulgated
the view that cleaner stoves might have a positive impact in all
situations.
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>An appropriate counterfactual is, “Stove smoke (the attributed cause) is not a detectable cause of pneumonia (the disease) in Malawian village children (the cohort).”  Removing (according to the GACC comparison chart) a large % of the PM from cooking made no difference that could be detected.
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>It does not prove the stove ‘is not clean enough’ because replacing the traditional stove with LPG also showed no detectable difference.  Does that suggest LPG is also not clean enough? Of course it does. The that is not a reasonable counterfactual either.

Point taken and agreed.

I would be happy for all people to be able to cook using gas (or even
Nikhil's favourite induction hob which I have yet to try) but it isn't
going to happen and we are concentrating on making stoves cleaner and
economical even though other efforts need to be made to reduce  the
air we breathe.

What I would like to follow up on is this swing from  attributing
problems to PM10 to the  smaller fractions. I believe you  mentioned
PM4 and below and Philip said their studies in mines found very small
particle (not black carbon?) of PM 1.5 to 0.5 to be retained in the
lungs.

Do we know if sooty particulates clump together to make larger
particles which are more easily filtered by the nasal passage or does
a fire always produce a whole range of sizes?

>From what I can see even sophisticated filters used in wealthy peoples
homes in polluted cities do not remove below pm2.5.

What data for a spectrum of particulate sizes is available for stoves?

Further to Frans' suggestion of modifying a cd player as a particulate
counter from back scattering of the light reflected from and
(individual?) particle instead of the pit in a silvered cd surface I
found this:

https://digitalmeans.co.uk/shop/sensors-category/sensors-air-category/pm25_sensor_module-laser_sensing

Perhaps this needs a change of subject line.

Andrew