Cooking Stoves, Indoor Air Pollution, and Respiratory Health in India
Last registered on October 03, 2016

Pre-Trial

Trial Information
General Information
Title
Cooking Stoves, Indoor Air Pollution, and Respiratory Health in India
RCT ID
AEARCTR-0001589
Initial registration date
October 03, 2016
Last updated
October 03, 2016 4:42 PM EDT
Location(s)
Region
Primary Investigator
Affiliation
Harvard University
Other Primary Investigator(s)
PI Affiliation
University of Chicago
PI Affiliation
MIT
Additional Trial Information
Status
Completed
Start date
2005-06-01
End date
2010-09-30
Secondary IDs
Abstract
Laboratory studies suggest that improved cooking stoves can reduce indoor air pollution, improve health, and decrease greenhouse gas emissions in developing countries. Researchers provide evidence, from a large-scale randomized trial in India, on the benefits of a common, laboratory-validated stove with a four-year follow-up. While smoke inhalation initially falls, this effect disappears by year two. Researchers find no changes across health outcomes or greenhouse gas emissions. Households used the stoves irregularly and inappropriately, failed to maintain them, and usage declined over time. This study underscores the need to test environmental technologies in real-world settings where behavior may undermine potential impacts.
External Link(s)
Registration Citation
Citation
Duflo, Esther, Michael Greenstone and Rema Hanna. 2016. "Cooking Stoves, Indoor Air Pollution, and Respiratory Health in India." AEA RCT Registry. October 03. https://www.socialscienceregistry.org/trials/1589/history/11006
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Experimental Details
Interventions
Intervention(s)
In collaboration with local NGOs, researchers in Orissa conducted an evaluation to measure the impact of improved cooking stoves (“chulas”) on individuals’ behavior and wellbeing. The stoves were constructed from mud and designed to have an enclosed flame and two pots to decrease cooking time, as well as a chimney to help ventilate the room. While the stoves were largely subsidized by the NGOs, households were responsible for providing the mud for the base, labor, and a payment of Rs.30 (about US$0.75) used to pay the person who assisted in building and maintaining the stoves. The total cost of the stove was approximately US$12.50. Households were also given training sessions on proper use and maintenance of stoves, and members of each village were hired to help promote use of the stoves and facilitate repairs if necessary.

A public lottery randomly assigned the order in which stoves were constructed within each village for 2,575 households. The stoves were distributed in three waves with the first wave receiving stoves in 2006, the second in 2009, and the third at the end of the evaluation. Households were followed for four years after initial stove offers, allowing for an examination of long-run use and impacts of stoves.
Intervention Start Date
2006-09-01
Intervention End Date
2010-09-30
Primary Outcomes
Primary Outcomes (end points)
Stove take-up and usage, smoke inhalation among primary cooks and children (by measuring Carbon Monoxide (CO) in exhaled breath), health effects among cooks, children, and infants, such as respiratory function, sore eyes, headache, phlegm, wheeze, tight chest, BP-systolic, BR-diastolic, earache, skin infection, vomit, weakness, abdominal pain, hearing problems, vision problems, worms, diarrhea. For primary cooks: FEV1, FEV1/FVCx100, cough or cold, any illness, health expenditures. For children aged 13 and under: BMI, cough, consult or fever, any illness, health expenditures, days of school missed last week. For infants: birthweight, infant mortality, stillbirths and miscarriages. Primary cooks and children: overall health index. Time and cost of operating stoves and self-reported satisfaction: total wood used at last meal, Total fuel (kg), costs last 30 days (rupees), time spent cooking last evening meal (minutes), Number of repairs made in the last year, Time spent on repairs in the last year (minutes).
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
In response to the health threats posed by the use of solid fuel in traditional stoves, as well as concerns about deforestation, both governments and nongovernmental organizations (NGOs) have been implementing clean stove programs for several decades. This paper evaluates an improved stove program run by Gram Vikas (GV), an NGO that operates in the state of Orissa. The stove considered in this study represents a relatively inexpensive improved stove technology. It is constructed with local materials and is low-cost at roughly US$12.50. GV subsidized the stove cost by contributing stove materials (chimney), design, and a skilled mason to supervise the construction. Households were responsible for providing mud for the stove base, labor and a payment of about US$0.75, which was used both to pay the mason who assisted in building and maintaining the stoves and to contribute to a fund for stoves for any new houses built in the village. As the stove is made from locally available materials, it can be easily constructed in these remote, rural areas of India.

In addition to providing the stoves, GV conducted the standard information campaigns that NGOs run when they introduce a new program for households that have won the lottery. Specifically, during construction GV held training sessions on proper use and maintenance. Among households that received a stove in the first wave, almost 70 percent report that they attended a training session. Moreover, GV identified individuals in each village who used their stoves correctly and hired (with a small stipend) them to promote proper use and alert GV when the stoves were in need of repair. Of those who received a stove in the first wave, 62 percent report knowing who this “promoter” is, 48 percent report that they attended a meeting with the promoter, and another 47 percent state that they received a visit from the promoter to discuss stove use. In total, about 86 percent report either having GV or the promoter provide training on the stove (either through a meeting or visit).

In the summer of 2005, GV obtained permission from 42 villages to participate in the study. In a decision unrelated to the study, three villages withdrew from all GV activity. As a result, researchers added five additional villages in June 2007. Therefore, a total of 2,575 households in 44 villages participated in the study. After researchers completed the baseline survey in each village (in 2006 for the majority of villages, and in 2007 for the additional five villages), a village meeting was conducted. At each meeting, GV explained that the stoves were being built in three waves, and that the households would be randomly assigned to each wave. Next, a public lottery (monitored by the research team) was conducted to choose the first third of households in the village that would be offered a GV improved stove. GV completed the first wave of stove construction and user training between September 2006 and March 2007. After the midline survey, the second round of village meetings occurred. A lottery was conducted to choose households that would be offered a stove in the second wave of construction. From May 2009 to April 2010, the second round of stove construction and training occurred. Throughout the study, researchers conducted a series of surveys to create a panel dataset on stove use, smoke exposure, health, stove breakages and repairs, and fuel use.

Researchers collected comprehensive data on the socio-demographic characteristics of each household. This data includes household composition (size, as well as each member’s age, sex, and relationship to the head of household), demographics (education levels, caste, religion), economic indicators (assets, indebtedness), and consumption patterns. In addition, for each household member, researchers collected measures of productivity, such as employment status, time-use patterns for adults over the last 24 hours, and school enrollment and attendance for children. Through a series of surveys, researchers collected information on stove use. This included the types of stoves a household owned, meals cooked with each type of stove over the previous week, repairs and maintenance activities surrounding the stoves, and fuel expenditures (both money and time). In addition, we collected information on beliefs about the efficacy of the stoves (for example, whether they use less fuel) and on satisfaction with the stoves. To measure smoke exposure, the team measured exhaled carbon monoxide (CO) with a Micro Medical CO monitor. CO is a biomarker of recent exposure to air pollution from biomass combustion, and therefore it can be used to proxy an individual’s personal exposure to smoke from their stoves. Furthermore, it is an inexpensive way to proxy for inhalation of particulate matter, which has been shown to be an important determinant of infant mortality and life expectancy.

Researchers collected two types of health data. First, they conducted detailed health recall surveys about symptoms (coughs, colds, etc.), infant outcomes, and health expenditures. Researchers complemented these data with physical health checks for biometric measurements, such as height, weight, and arm circumference. During the physical health check, they administered spirometry tests designed to gauge respiratory health by measuring how much air the lungs can hold and how well the respiratory system can move air in and out of them. In contrast to peak flow tests, which are easier to administer, spirometry readings can be used to diagnose obstructive lung disorders (such as chronic obstructive pulmonary disease (COPD) and asthma), and also restrictive lung disorders. Further, this test is the only way to obtain measurements of lung function that are comparable across individuals. The tests were conducted using the equipment directions, as well as guidelines from the American Association for Respiratory Care. Finally, throughout the study, researchers compiled Gram Vikas’s administrative data, i.e., data on lottery participation, treatment status, and outcomes.

Most of the evidence on health improvements from reductions in indoor air pollution is based on the association between clean stove usage and health in observational data. However, those who choose to use a clean stove may generally value health more than those who do not and thus may also undertake other health investments, either of which would lead to better health. In this case, our estimated coefficients would be biased upwards. Alternatively, the improved stoves may be disproportionately used by the sick, which would cause the estimated relationships to be biased downwards. The experimental design we propose allows us to solve these endogeneity problems by comparing winners and losers from the stove lottery.

Researchers estimate the reduced form effect of winning the stove on a series of outcomes, including stove use, CO exposure, health, and other non-health stove outcomes (such as fuel use and cooking time). In their model, researchers include village survey month-year fixed effects, i.e., there are separate fixed effects for all observations from a village in a given month-year (e.g., January 2010). For CO exposure, health, and non-health stove outcomes (when possible) researchers additionally include the baseline value of the outcome to gain additional precision. Researchers also estimate how the treatment effect varies over time, as the effect of being offered a stove may change throughout time for a variety of reasons. To do that, they interact the treatment effect with a set of indicator variables for whether the observation falls within a given year after stove distribution. To scale the results, researchers estimate the effect of using any type of low-polluting stove on CO exposure using an instrumental variables strategy. Finally, the household-level equations are weighted to account for household splits and mergers. For all regression analysis, the standard errors are clustered at the household level, which is the unit at which the treatment was assigned.
Experimental Design Details
Randomization Method
Public lottery
Randomization Unit
Household
Was the treatment clustered?
Yes
Experiment Characteristics
Sample size: planned number of clusters
2,600 households (A public lottery determined the order in which stoves were constructed within each village for 2,600 households).
Sample size: planned number of observations
NA; treatment is clustered
Sample size (or number of clusters) by treatment arms
Treatment 1: 867 households, Treatment 2: 867 households, Treatment 3/control: 866 households (The first third of households within each village received the stoves at the start of the project, the second third received the stoves about two years after the first wave, and the remaining households received them at the end.)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
New York University
IRB Approval Date
Details not available
IRB Approval Number
Details not available
IRB Name
Harvard University
IRB Approval Date
Details not available
IRB Approval Number
Details not available
IRB Name
MIT
IRB Approval Date
Details not available
IRB Approval Number
Details not available
Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
Yes
Intervention Completion Date
September 30, 2010, 12:00 AM +00:00
Is data collection complete?
Yes
Data Collection Completion Date
September 30, 2010, 12:00 AM +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
2,575 households in 44 villages
Was attrition correlated with treatment status?
No
Final Sample Size: Total Number of Observations
Primary cooks: 4,234; Children: 4,401
Final Sample Size (or Number of Clusters) by Treatment Arms
Treatment 1: 858 households, Treatment 2: 858 households, Treatment 3/control: 859 households
Data Publication
Data Publication
Is public data available?
Yes
Program Files
Program Files
Yes
Reports and Papers
Preliminary Reports
Relevant Papers
Abstract
Indoor air pollution emitted from traditional fuels and cooking stoves is a potentially large health threat in rural regions. This paper reports the results of a survey of traditional stove ownership and health among 2,400 households in rural Orissa. Researchers find a very high incidence of respiratory illness. About one-third of the adults and half of the children in the survey had experienced symptoms of respiratory illness in the 30 days preceding the survey, with 10 per cent of adults and 20 per cent of children experiencing a serious cough. Researchers find a high correlation between using a traditional stove and having symptoms of respiratory illness. Researchers cannot, however, rule out the possibility that the high level of observed respiratory illness is due to other factors that also contribute to a household’s decision to use a traditional stove, such as poverty, health preferences and the bargaining power of women in the household.
Citation
Duflo, Esther, Michael Greenstone, and Rema Hanna. 2008. "Cooking Stoves, Indoor Air Pollution, and Respiratory Health in Rural Orissa." Economic & Political Weekly 43(32): 71-76.
Abstract
Indoor air pollution (IAP) caused by solid fuel use and/or traditional cooking stoves is a global health threat, particularly for women and young children. The WHO World Health Report 2002 estimates that IAP is responsible for 2.7% of the loss of disability adjusted life years (DALYs) worldwide and 3.7% in high-mortality developing countries. Despite the magnitude of this problem, social scientists have only recently begun to pay closer attention to this issue and to test strategies for reducing IAP. In this paper, researchers provide a survey of the current literature on the relationship between indoor air pollution, respiratory health and economic well-being. Researchers then discuss the available evidence on the effectiveness of popular policy prescriptions to reduce IAP within the household.
Citation
Duflo, Esther, Michael Greenstone, and Rema Hanna. "Indoor air pollution, health and economic well-being." SAPIEN. S. Surveys and Perspectives Integrating Environment and Society 1.1 (2008).
Abstract
NA
Citation
Web Appendix to Hanna, Rema, Esther Duflo, and Michael Greenstone. "Up in Smoke: The Influence of Household Behavior on the Long-Run Impact of Improved Cooking Stoves." American Economic Journal: Economic Policy 8, no. 1 (2016): 80-114.
Abstract
Laboratory studies suggest that improved cooking stoves can reduce indoor air pollution, improve health, and decrease greenhouse gas emissions in developing countries. Researchers provide evidence, from a large-scale randomized trial in India, on the benefits of a common, laboratory-validated stove with a four-year follow-up. While smoke inhalation initially falls, this effect disappears by year two. Researchers find no changes across health outcomes or greenhouse gas emissions. Households used the stoves irregularly and inappropriately, failed to maintain them, and usage declined over time. This study underscores the need to test environmental technologies in real-world settings where behavior may undermine potential impacts.
Citation
Hanna, Rema, Esther Duflo, and Michael Greenstone. "Up in Smoke: The Influence of Household Behavior on the Long-Run Impact of Improved Cooking Stoves." American Economic Journal: Economic Policy 8, no. 1 (2016): 80-114.