[Stoves] report with dissapointing results from cleaner cookstoves (Crispin)

[Crispin Pemberton-Pigott]

Dear Ron

Some comments on your comments:

>DALY and ADALY (respectively in years and $) are many places below, but a simple start is https://en.wikipedia.org/wiki/Disability-adjusted_life_year .  I encourage all readers to decide if these are valid units - and if not what should replace them.  Nikhil says they are bogus numbers

Depending on what you mean by ‘bogus’ I agree with Nikhil. The results are estimations agreed by committee and are not reflective of some real situation where we know with any precision what contributes someone premature or post-mature death.  The concept of a ‘mature death’ is itself fraught. Is it three score and ten, of 86? Half of all people, by definition, die post-maturely. Obviously some of them were exposed to stove smoke. How much more post-maturely would they have died if they had not been exposed? How can anyone credibly put a number on that?

>WHO = World Health Organization;  they sponsored a webinar featuring Dr. Michael Johnson - who developed a nice model disparaged (above) by Nikhil.

I am not sure why you call the exposure model ‘nice’. It is primitive compared with the model contained in their own committee papers, which they failed to use even though it is stated by be much closer to modeling reality. My complaint about using the single box model instead of their own three box model is that the three box model calculates an exposure that is less than half of that calculated by the single box model. It means at stove can emit twice as much smoke and ‘be safe’ according to them. So why would they use a model that they admit reflects exposure poorly?

For those with good memories, the modeling of exposure done by Prof KK Prasad at the University of Eindhoven in 1982 (etc) was quite superior to the three box model. It shows even less exposure. How is it that more than 30 years later with all the super computers around, we have to use a silly single box model to estimate exposure when Prof Prasad far surpassed the method decades ago? Does the WHO and Berkeley only have Apple II’s at their disposal?

>http://www.who.int/indoorair/guidelines/hhfc/recommendation_3/en/  explains why NOT to use coal as a fuel  (this re a topic raised in the exchange below)

This is so out of date as to be embarrassing.

“Unprocessed coal* should not be used as a household fuel.
(*Unprocessed coal is that which has not been treated by chemical, physical, or thermal means to reduce contaminants.)

“Three reasons guide this recommendation, over and above the documented health risks from products of incomplete combustion of solid fuels:
• The International Agency for Research on Cancer has concluded that indoor emissions from household combustion of coal are carcinogenic;
• In those parts of the world where it is most extensively used as a household fuel and the evidence base is strongest, coal contains toxic elements, such as fluorine, arsenic, lead, selenium and mercury, which are not destroyed by combustion; and
• Technical constraints make it difficult to burn coal cleanly in households.


1.       It ascribes emission to the fuel, not the combustor.

2.       It assumes that coking coal ‘removes the smoke’.

3.       The IARC has never tested a modern coal-burning stove that procures no PM.

4.       Having just said that the coal should be ‘processed’ to remove ‘contaminants’ (by which they obviously mean the volatiles that are cleanly combusted in a modern stove) they assert that the contaminants are not removed by such treatment, being inherent in the fuel. This is a deliberate confabulation of the products of incomplete combustion of coal in a poor combustor, and the inherent properties of coals that contain “fluorine, arsenic, lead, selenium and mercury” in toxic amounts.

5.       All food also contains “fluorine, arsenic, lead, selenium and mercury”. What matters is how much.

6.       The pretense was offered in the introduction to the Stove Comparison Chart document that all coal has to be abandoned because somewhere in SW China there is coal with a very high level of arsenic. Well, there are fish with a high level of methyl mercury – does that mean all fish on the planet should be avoided?

7.       Just because the WHO and IARC don’t know how to burn coal cleanly should not restrain those who are actually doing something about the problem of pollution from coal combustion.

These are good links to start with. Thanks.

>GBD = Global Burden of Disease;  see http://thelancet.com/gbd
IER= Integrated Exposure Response
http://www.who.int/phe/health_topics/outdoorair/databases/AAP_BoD_methods_March2014.pdf

This is disingenuous to say the least:

>I am only a beginner (and expect to stay that way) on this part of stove science.  I suggest the task of this list’s members is to decide whether Nikhil and Crispin are better authorities on the topic of this exchange than the cites above.  Everyone is welcome to trust Nikhil and Crispin on these matters, but I tend to trust the stove side of all this presented by Prof.  Kirk Smith of UC-Berkeley - who I believe would not agree with much of their below exchange.

See http://static.squarespace.com/static/53856e1ee4b00c6f1fc1f602/538570c1e4b071a53f15e518/538570d9e4b071a53f15e9cc/1401254105672/DFID-SE4.pdf?format=original

Please see slide No.2 which shows how the GBD has been allocated in India. Note that these numbers are not ‘measured’ they are population estimates. Important for our discussion is the attribution-by-committee to the ‘chronic respiratory diseases’ with household air pollution presented as a risk factor, raising it from ≈4.4 to 6.1. This has been squarely rebutted by the Malawi stove health impact study. Because the attribution is not based on measurements of people, it reflects a committee decision.

As for ‘believing Nikhil or Crispin’, we raised the matter comparing the allocation-by-committee and the results of an actual large scale investigation in Malawi. The only position remaining that could defend the content of Slide 3 is if disease in India has different causes than the same disease in Malawi. As the DALY calculations makes the assumption they are the same, then the slide is challenged by the study.

>This graph from about 20% through the Ppt is key to our stove work.  I am now checking whether it likely that any stove (likely to be a TLUD) can get to the WHO-desired 10 ug/m3 (without a chimney).  Anyone know?

It is slide 12.

[cid:image001.png at 01D25211.C3FB3E70]

The contents of the slide are based on allocations-by-committee and have no underlying data. When the study in Malawi was funded, the intention was to get the data necessary to bolster the claims made in Slide 12. The real world challenges the assertions of the good Professor Kirk Smith and the GBD committee and the creators of the DALYs.

Childhood pneumonia was unaffected by changing the exposure to cooking fire smoke. Big scale, proper field study. If you don’t believe the study, you can instead believe Prof Smith.

Further: the “calculation” of the WHO’s exposure to stove smoke is fanciful, literally. The emissions from a stove cannot be used, with any WHO method proposed so far, to tell us what exposure to that smoke is. When the room is smoky, people leave it. When the day is hot, people open the door. When it is cold they close the window. When they are cooking for a long time, they load the fuel and go and do something else for a while. There is literally no way the emission rate can be used to calculate the exposure, and therefore the reduction in exposure, to stove smoke.

So what do the WHO people do? They model a range of emissions from a range of stoves and a range of kitchen architectures, and a range of air turnover rates, then calculate an instantaneous dispersion of all smoke from those stoves throughout the room and assume the cook is always present. Then they assume all PM2.5 is equally toxic, both coal smoke and wood smoke and LPG PICs and everything. Then they estimate the exposure and the consequences of that exposure using charts like slide 3 and 12 from Kirk. Then they say x is acceptable and y is not.

This is witchcraft! By changing the assumptions you can produce any result you want. And what they wanted was a clear association between stove smoke and childhood pneumonia and COPD. They didn’t get it when they finally went to the field looking. Does it mean it is not there? We truly don’t know. And when we don’t know, we can make the assertion that ‘it is probably there, trust me’.

Kirk’s presentation goes on with the usual ads for propane and electricity. That is fine by itself, but no one is going to bankrupt a country to provide LPG so cheaply that everyone use it in place of solid fuels.

This Stoves discussion site is marvellous for presenting a place for inventions and concepts to be presented that get us past the one-size-fits-all “if I ruled the world’ development mentalities. On size does not fit all and no one rules the world.

The first, simplest, most obvious, clear response that should be made with cooking smoke is to get it outdoors where it is heading anyway. Put on a chimney. It vastly improves indoor air quality in a single day. And whose voices are loudest in protesting this simple and effective solution?  Do your own homework. It won’t take long to find out where the problem lies.

On slide 49 Kirk says two wise things: [and my comments]

“Make the available clean” [put in a hood or chimney and clean up the combustion]
“Embrace leap-frog technologies” [accept that there are now wood and coal, kerosene and ethanol-burning stoves that are as clean as LPG]

This is a little more wobbly:

“Act recognising that it is primarily a health issue.”

Nikhil correctly asks,
“To whom is it primarily a health issue?”  Health experts, of course.
To whom is it primarily a fuel processing issue? Fuel processing businesses, of course.
To whom is it primarily a stove design issue? To stove designer, of course.
To whom is it primarily an LPG distribution issue? LPG vendors, of course.
To whom is it primarily an electricity grid extension issue? Electricity generators, of course.
To whom is it primarily a funding issue? Grant recipients, of course.

If all you have is a hammer, everything is defined as a nail.
Crispin


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