[Stoves] health impact follow-up (fixed broken image)

[Ronal W. Larson]

Stove list,  cc Marc

	1.  Like Paul Anderson,  I have communicated with Marc Pare  (Pronounce as Paar-ay) for a few years- and want to support Paul’s observation that Marc’s view is worth listening to.  Marc did some very nice work with char-making units to solve a serious emissions problem for brick kilns in Vietnam.  See http://www.vrac.iastate.edu/ethos/files/ethos2013/Room%202/Sunday%20PM/Excess%20Air%20Calculations.pdf

	2.   On 23 August, I sent this list a message including the full very recent Science magazine editorial by Prof. Kirk Smith - where Kirk urged cooking with electricity  (earlier Kirk has proposed fossil fuels for the same health reasons).  Until Marc’s work, I had been resisting this option - thinking that char-making stoves could possibly still do the job, and wanting to stay away from everything fossil.  Now less strongly resisting (and note that the liquid fuel world can also be biomass-based and can involve biochar.  As Paul Anderson has pointed out, char-making stoves are not on Kirk’s “stoves death plot” - so I am not certain that we can get down to the lower left corner of that plot.  But we might.  

	3.  In conversation with Kirk Harris and Dean Still, I have learned that in very recent (unreported) Aprovecho testing on Kirk’s unit, most of the CO and PM tests were well over an “ISO” rating of 4.0 - one getting as high as 4.8.  Unfortunately, these ISO-PM units don’t match those used in the Kirk Smith “”stove death plot”.  Can anyone make a conversion for us?  There is no reason to think that 4.8 as an ISO number is a maximum on what can be achieved.  With these numbers, we get much closer to the origin - and therefore do much better than the 20% possibility if we only compare to Rockets.

	4.  Turning to Marc’s questions, we should also note that some of the deaths are due to CO - especially in the many households where charcoal use is high.  Again, char-making stoves do well there, but charcoal-using do not.   See this pdf to show how some of this ISO language was being proposed in 2013:
http://www.vrac.iastate.edu/ethos/files/ethos2013/Room%202/Sunday%20AM/Standardized%20Stove%20Reporting%20for%20IWA%20Tiers%20of%20Performance%20and%20the%20Stove%20Performance%20Inventory.pdf

	5.  My orientation on char-making stoves started off as forest preservation, then health (Kirk’s focus), then time and cost saving and for the last 7-8 years mainly on climate issues.   So I can understand that Kirk’s dominant health issue may not be resolved with char-making stoves (but I still think it might).  But even with a strong emphasis on 100% cooking with electricity, the low first and high efficiency of induction cookers will still leave a monthly cost beyond the means of many - for many years - because electricity is high cost when you are poor and wood is cheap and nearby.  So we should still keep striving for improvement on char-making stoves - that do a lot more than reduce DALY’s.

	6.  There is a great chance that electric cooking in India (and everywhere) can be 100% renewable (zero fossil) in a few decades (can be carbon neutral).   The costs of solar and wind electricity are possibly already competitive in India and will get better.  And ways will be found to put in enough storage and/or biomass electric to get 100% reliability,  But that would not guarantee the carbon negativity that we need.  But (good news?)  I decided only yesterday that such an event might also be possible with fuel cells and biomass (and carbon negativity)  Fuel cells are already routinely at 50% efficiency and some at 60%.  And some fuel cells are using biomass fuels - and certainly are talking about the RE option.  But I have found no-one talking about solid oxide fuel cells (SOFC), biomass, and carbon negativity (char-making).  I will add a few more words on the biochar list about this possibility later today.  This is unlikely to ever be a major stoves topic  (but might add electricity generation via char making stoves) — but it is certainly a new biochar and (apparently also a new) SOFC topic).  So I am not too concerned about switching away from char-making (carbon negative) stoves - as long as enough of the electricity can have the same carbon negative benefits (soil and climate improvement, etc).  Note that liquid fuels can also have this carbon negative (charcoal) characteristic - so liquids could eventually compete with electricity on both cost and health metrics.

Ron

On Sep 4, 2014, at 11:23 PM, Marc-Antoine Pare <marcpare0 at gmail.com> wrote:

> Hi everyone,
> Thanks for the discussion so far. I've looked at the health numbers for improved cook stoves in some more detail.
> I found two major approaches to quantifying the impact on health by stoves: long term studies and modeling based on exposure response.
> They both point to the same overall conclusion: improved biomass cook stoves will only reduce a small number of the “4 million deaths” you hear about from indoor air pollution.
> Also, it appears that there isn't an existing biomass technology that will!
> Please bear in mind that this is just a few days of compiling results from research. All of these conclusions are tentative. I welcome any and all criticism. The reading has been quite educational so far.
> One note at the start: the studies here consider the negative effects on respiratory health by particulate matter (PM). The studies I read note that this is by far the largest contributor to the burden of disease from indoor air pollution.
> 
> Long-term studies
> Effect of reduction in household air pollution on childhood pneumonia in Guatemala (RESPIRE): a randomised controlled trial (2011)
> 523 households involved. About half get an improved plancha stove, which reduces exposure about 50%. Eighteen months later, there was a 22% reduction in cases of pneumonia.
> Note that in this population, there were 9 deaths attributed to pneumonia. This is important later.
> Also important to note is that aid workers regularly coached these households in usage and maintenance.
> 
> A Recipe for Success? Randomized Free Distribution of Improved Cooking Stoves in Senegal
> 98 households get a stove for one year. Respiratory disease symptoms for cooking women drop by 8%.
> 
> UP IN SMOKE: THE INFLUENCE OF HOUSEHOLD BEHAVIOR ON THE LONG-RUN IMPACT OF IMPROVED COOKING STOVES
> 5 years, 15,000 Indian households (!) “We find no evidence of improvements in lung functioning.”
> The critique of this study is that they used mud stoves with chimneys that weren't all that clean-burning.
> What the long-term studies tell us
> I was surprised that the number of stoves required to impact health was so high. In the Guatemala study, you need 250 stoves to prevent about 10 cases of pneumonia.
> Another interesting thing to note is that I didn't find any studies that monitor big enough populations for long enough to quantify how many deaths are prevented by improved stoves. Again, in the Guatemala study, the stoves saved somewhere between 1-5 lives. This number is so small that it's really tough to extrapolate it at all.
> Clearly something funny is going on here. Why exactly are the numbers so small? Did people use the stoves incorrectly? Would better stoves have helped? And why did nothing happen in India?
> One approach to answering these questions is to dig in to the mechanism for saving lives with stoves. We do this with the exposure response to pollutants.
> 
> Modeling based on exposure-response
> Health impact from exposure to PM is well studied. Exposure amount predicts quite accurately future health problems. This is great because it let's us start answering the question: just how clean do stoves need to get to meaningfully impact health?
> We can really get into a lot of detail here. It's a dissertation's worth of calculation to come up with these numbers (see: THE DEVELOPMENT OF NUMERICAL TOOLS FOR CHARACTERIZING AND QUANTIFYING BIOMASS COOKSTOVE IMPACT)
> Kirk Smith presented a summary of what exposure-response can tell us about stoves at the Clean Cooking Conference just this May.
> Here's the graph:
> [attached]
> The key note is that a rocket stoves “leaves ~80% of the burden [of disease] untouched”. That means that even if we give everyone a rocket stove, only 20% of the 4,000,000 deaths from IAP will be affected.
> Here's the reasoning. The red line in the graph is called the “exposure-response relationship”. It's a log-linear relationship. That means that most of the damage from PM exposure occurs from zero exposure to a very small amount of exposure.
> It turns out that improved cook stoves – even the very fancy fan stove developed by Phillips – don't reduce emissions below that initial amount of very dangerous exposure.
> Kirk Smith provided this summary in London: “Current Health Evidence shows now that even major reductions (<90%) in emissions still lead to small health improvements”
> 
> Conclusions: just how small?
> We can do a back-of-the-envelope analysis to tell the story of the numbers presented here. If we assume six billion people use primitive stoves, then one hundred million of them is 1/60 of the total. 1/60 of the four million deaths worldwide is ~67,000. Rocket stoves would save 20% of those lives according to the exposure-response model: just 13,400.
> So, you get out 100,000,000 stoves, and you save 13,400 lives. This also assumes that you achieve the PM emissions reductions in practice. There are mountains of evidence (academic and practical) that this is not the case. 
> I am trying to find what I am missing here. I really expected the link to be much more clear and significant. Is there some other reason that stoves are promoted besides health benefit? Is there some overarching strategic goal that I'm missing?
> Really, I'm looking for some number to tell the story. All the numbers I have found point to the fact that stoves, even the very best ones we have, won't move the needle on deaths from IAP.
> I would be very happy to be wrong about this. I know that development issues can be confoundingly complex, and I would welcome another perspective on this.
> One silver lining to all of this is that I think it would be great for technology developers to hear that current technologies are totally inadequate. There's nothing like an impossible challenge to galvanize the inventor :)
> - Marc Paré
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