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Monday, June 4, 2012

Up in Smoke: The Influence of Household Behavior on the Long-Run Impact of Improved Cooking Stoves

http://papers.nber.org/papers/w18033 
It is conventional wisdom that it is possible to reduce exposure to indoor air pollution, improve health outcomes, and decrease greenhouse gas emissions in the rural areas of developing countries through the adoption of improved cooking stoves. This belief is largely supported by observational field studies and engineering or laboratory experiments. However, we provide new evidence, from a randomized control trial conducted in rural Orissa, India (one of the poorest places in India), on the benefits of a commonly used improved stove that laboratory tests showed to reduce indoor air pollution and require less fuel. We track households for up to four years after they received the stove. While we find a meaningful reduction in smoke inhalation in the first year, there is no effect over longer time horizons. We find no evidence of improvements in lung functioning or health and there is no change in fuel consumption (and presumably greenhouse gas emissions). The difference between the laboratory and field findings appear to result from households’ revealed low valuation of the stoves. Households failed to use the stoves regularly or appropriately, did not make the necessary investments to maintain them properly, and usage rates ultimately declined further over time. More broadly, this study underscores the need to test environmental and health technologies in real-world settings where behavior may temper impacts, and to test them over a long enough horizon to understand how this behavioral effect evolves over time.



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The World Health Organization lists “indoor air pollution (IAP) from primitive household cooking fires as the leading environmental cause of death in the world,” stating that “it contributes to nearly 2.0 million deaths annually,” about as many deaths as malaria and tuberculosis combined (Martin, Glass, Balbus, and Collins, 2011). Moreover, cooking with biomass fuels is a key source of climate change through its releases of carbon dioxide (CO2) and black carbon (Kandlikar, Reynolds, and Grieshop 2009). In response, improved cooking stoves are increasingly seen as a tool to improve respiratory health and combat climate change.  For example, in September 2010, Hillary Clinton announced the formation of the Global Alliance for Clean Cookstoves (GACC), which calls for 100 million homes to adopt clean and efficient stoves and fuels by 2020. However, this big push for improved cooking stoves has occurred despite surprisingly little rigorous evidence on their efficacy on health and fuel use.

Gram Vikas (GV), an award winning nongovernmental organizations (NGO), obtained funding to subsidize stove construction for 15,000 households over five years, independent of the research.3 GV chose stoves designed with an enclosed cooking chamber (to keep the flame separate from the food) and a chimney to direct smoke away from the user. The stoves had been proven to reduce IAP and energy consumption in laboratory settings and could be constructed with locally sourced materials, facilitating distribution at a large scale. At a total cost of about US$12.50, these stoves fall within the “lower end” of improved stove technologies. However, these stoves represent the vast majority of improved stoves that have been distributed....
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(annual per-capita consumption of households in the sample is $145).
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The RESPIRE stoves cost between $100 and $150, which makes them prohibitively expensive for most households where indoor air pollution is a problem.
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Households were responsible for providing mud for the stove base, labor and a payment of about US$0.75, which was used to pay the mason who assisted in building and maintaining the stoves, as well as a fund for new stoves if a new house is built in the village.
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The households were very poor, with an average monthly per capita household expenditure of about US$12 (Rs 475).
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Relatively speaking, health expenditures were high, with females reporting that they spent about US$1.63 in the last month.
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The fraction of households that destroyed their stove, presumably to create space in their homes, increased from 2 percent in Year 1 to 32 percent by Year 4.
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For the sample of those who own a stove in good condition, only about 60 percent report that they use the stoves properly, where proper use is defined as cleaning the stove in the last week, using the stove in the last week, not elevating the cook pot during use, and using the two pots correctly.
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On average, we observe limited effects on the CO concentrations in respondents’ breath. For women, CO levels fall slightly, but the effect is not significant.  The magnitude of this effect is 1.5 percent of the mean and 1.6 percent of a standard deviation.
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On average, owning at least one of any low-polluting stoves reduces CO levels by -0.286 ppm for women, -0.564 ppm for primary cooks, and -0.478 ppm for children. These scaled estimates suggest declines of 4.1 percent, 7.9 percent, and 8.8 percent, respectively, in smoke exposure from owning an improved stove, but none of them are statistically different from zero. Owning an improved cooking stove in the first year reduces CO exposure for primary cooks by -0.898 ppm, or 12.5 percent, relative to the control group (Table 6, Panel B, Column 3). However, by Year 2, this falls to -0.468 ppm and is no longer statistically significant. By Years 3 and 4, the effect becomes positive and remains statistically indistinguishable from zero.
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Out of 44 health estimates, five (11 percent) are significant at the 10 percent level, which is what would be expected by chance. All five of the statistically significant effects have a counterintuitive signs, suggesting that the stove offer causes worse health, further underscoring that treatment status appears unrelated to health.
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On average, households seem to have been convinced that they should use less wood in the new stoves: more than 60 percent of households report that they believe that GV stoves use less wood (Appendix Figure 6). However, looking at actual use, wood use appears unchanged, while total fuel expenditures increases, although the increase is only statistically significant in Year 4. The discrepancy between the laboratory test and the actual expenditures by the households may be due to improper use, or the fact that households now use both the traditional and the improved stove, perhaps simultaneously. Burwen and Levine (2011) observe a similar effect for the type of stove that they evaluate in Ghana. After eight weeks, households took less time and fuel to cook a meal in a carefully controlled test, but there was no significant decline in the actual fuel used by the family. These results underscore that using laboratory or engineering tests to justify fuel
efficiency gains for carbon credit calculations has the potential to be extremely misleading.

Similarly, most households believe that the stoves reduce cooking time. However, we find that, if anything, the stoves increased the time spent cooking evening meals by about four minutes, although this is not statistically significant at conventional levels.

Finally, we examine the total repairs to both the improved and traditional stoves. Control households state that they repair their stoves about once a month. Treatment households made, on average, about 2.5 more repairs to their stove in the last year, translating to about 4.5 hours of time over the last year. These two effects are economically large, implying increases of 20.2 percent and 68.7 percent, respectively, and are statistically significant.

Despite the fact that GV stoves increase household costs and fail to improve health, households generally report that they are satisfied with the stoves. On a scale from one to ten with one being the best, those who obtained an improved stove rate their satisfaction with it at 2.87, with 89 percent of households happy to recommend the stoves to others. The top reasons for recommending the stoves include that they emit less smoke in the household, the household belief that they require less fuel, the two-pot functionality, and the households belief that they require less time to cook.

The full paper is currently available free of charge at web.hks.harvard.edu/publications/getFile.aspx?Id=783.

by Rema Hanna, Esther Duflo, Michael Greenstone
National Bureau of Economic Research (NBER) www.NBER.org 
NBER Working Paper No. 18033; Issued in May 2012

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