Indoor Air Quality Updates
Women, Energy and Economic Empowerment – Boiling Point, Issue 66, 2015.
This issue’s theme on Women, Energy and Economic Empowerment shines light on the role of women in reaching energy products and services to the poor and ‘difficult to reach’ consumers. The issue also explores the impact that women led micro and small enterprises (MSEs) selling energy services can have, with respect to household spending, poverty, gender equality and local markets and economies. Because of their role as household energy managers and through their formal and informal networks, women are in a unique position to connect with their peers, increase awareness and deliver energy products and services.
As users, they know what features energy products should have. At the same time, when women who are home-based micro and small scale business owners or workers get energy access, they stand to benefit tremendously through increased productivity and lowered costs, resulting in increased incomes benefitting families, societies and local markets. ENERGIA taps into this huge potential of women-led MSEs in scaling up energy access with its recently launched Women’s Economic Empowerment Programme (WE).
Improved stove interventions to reduce household air pollution in low and middle income countries: a descriptive systematic review
Improved stove interventions to reduce household air pollution in low and middle income countries: a descriptive systematic review. BMC Public Health, July 2015.
Authors: Emma Thomas, Kremlin Wickramasinghe, et al.
Background: Household air pollution (HAP) resulting from the use of solid fuels presents a major public health hazard. Improved stoves have been offered as a potential tool to reduce exposure to HAP and improve health outcomes. Systematic information on stove interventions is limited.
Methods: We conducted a systematic review of the current evidence of improved stove interventions aimed at reducing HAP in real life settings. An extensive search of ten databases commenced in April 2014. In addition, we searched clinical trial registers and websites for unpublished studies and grey literature. Studies were included if they reported on an improved stove intervention aimed at reducing HAP resulting from solid fuel use in a low or middle-income country.
Results: The review identified 5,243 records. Of these, 258 abstracts and 57 full texts were reviewed and 36 studies identified which met the inclusion criteria. When well-designed, implemented and monitored, stove interventions can have positive effects. However, the impacts are unlikely to reduce pollutant levels to World Health Organization recommended levels. Additionally, many participants in the included studies continued to use traditional stoves either instead of, or in additional to, new improved options.
Conclusions: Current evidence suggests improved stove interventions can reduce exposure to HAP resulting from solid fuel smoke. Studies with longer follow-up periods are required to assess if pollutant reductions reported in the current literature are sustained over time. Adoption of new technologies is challenging and interventions must be tailored to the needs and preferences of the households of interest. Future studies require greater process evaluation to improve knowledge of implementation barriers and facilitators
USAID and Global Alliance for Clean Cookstoves Jointly Fund Research on Clean Cooking Adoption
July 2015 – The USAID Translating Research into Action Project (TRAction) and the Global Alliance for Clean Cookstoves (the Alliance) are funding three research projects to study the adoption of clean cooking technology to reduce household air pollution.
TRAction and the Alliance aim to better understand the barriers and motivators for using clean cooking technology through these research awards, which will be implemented by teams from the University of North Carolina (UNC), University of California-San Francisco (UCSF), and the Kintampo Health Research Center. All research studies will commence in June 2015.
Read more on the Alliance website.
Targeting Household Air Pollution for Curbing the Cardiovascular Disease Burden: A Health Priority in Sub-Saharan Africa.
Targeting Household Air Pollution for Curbing the Cardiovascular Disease Burden: A Health Priority in Sub-Saharan Africa. The Journal of Clinical Hypertension, July 2015.
Authors: Jean Jacques N. Noubiap, Mickael Essouma and Jean Joel R. Bigna
Household air pollution (HAP) is a major public health problem, particularly in sub-Saharan Africa where most of the populations still rely on solid fuels for cooking, heating, and lighting. This narrative review highlights the direct and indirect evidence of the important role of HAP in cardiovascular disease, especially in sub-Saharan African countries where highest rates of major cardiovascular disease and death are observed, and thus provides ample reason for promotion of preventive interventions to reduce HAP exposures in the region. There is an urgent need for efficient strategies to educate populations on the health issues associated with this health hazard, to provide affordable clean cooking energy for poor people and to promote improved household ventilation. High-quality data on household energy practices and patterns of HAP and related health issues are still needed for efficient policy making in this region.
Cluster-randomized controlled trial to evaluate the Rwanda Ministry of Health and DelAgua Health “Tubeho Neza” large-scale distribution of cookstoves and water filters in Western Province, Rwanda
Cluster-randomized controlled trial to evaluate the Rwanda Ministryof Health and DelAgua Health “Tubeho Neza” large-scale distribution of cookstoves and water filters in Western Province, Rwanda, 2015. DelAgua.
Authors: Thomas Clasen, Corey Nagel, Evan Thomas
Preliminary results suggest that after 2 years, the Phase 1 program achieved a 46% reduction in diarrhoea in children under 5, a 73% reduction in household air pollution for families cooking outdoors, and a 27.7% reduction in cookstove emission exposure among children. If similar reductions are sustained throughout Phase 2, this program may save more than 30 children’s lives a year, and avert over 2,500 disability-adjusted life-years (DALYs) annually.
Household and community poverty, biomass use, and air pollution in Accra, Ghana. Proc Natl Acad Sci U S A. 2011 Jul 5.
Authors: Zheng Zhou, Kathie L. Dionisio, et al.
Many urban households in developing countries use biomass fuels for cooking. The proportion of household biomass use varies among neighborhoods, and is generally higher in low socioeconomic status (SES) communities. Little is known of how household air pollution varies by SES and how it is affected by biomass fuels and traffic sources in developing country cities. In four neighborhoods in Accra, Ghana, we collected and analyzed geo-referenced data on household and community particulate matter (PM) pollution, SES, fuel use for domestic and small-commercial cooking, housing characteristics, and distance to major roads.
Cooking area PM was lowest in the high-SES neighborhood, with geometric means of 25 (95% confidence interval, 21–29) and 28 (23–33) μg/m3 for fine and coarse PM (PM2.5 and PM2.5–10), respectively; it was highest in two low-SES slums, with geometric means reaching 71 (62–80) and 131 (114–150) μg/m3 for fine and coarse PM. After adjustment for other factors, living in a community where all households use biomass fuels would be associated with 1.5- to 2.7-times PM levels in models with and without adjustment for ambient PM.
Community biomass use had a stronger association with household PM than household’s own fuel choice in crude and adjusted estimates. Lack of regular physical access to clean fuels is an obstacle to fuel switching in low-income neighborhoods and should be addressed through equitable energy infrastructure.
Lessons From Rural Madagascar on Improving Air Quality in the Kitchen. Jnl Environ Dev, June 2015.
Authors: Susmita Dasgupta, Paul Martin. Hussain A. Samad
The World Bank, Washington, DC, USASusmita Dasgupta, The World Bank, 1818 H Street, Washington, DC 20433, USA. Email: firstname.lastname@example.org
Household air pollution is the second leading cause of disease in Madagascar, where more than 99% of households rely on solid biomass for cooking. This article presents findings and conclusions from an initiative to monitor household air pollution in rural Madagascar. The average concentrations of fine particulate matter and carbon monoxide in kitchens significantly exceeded World Health Organization guidelines for indoor exposure. A fixed-effect panel regression analysis was conducted to investigate the effects of fuel (charcoal, wood, and ethanol), stove (traditional, improved charcoal and wood, and ethanol), kitchen size, ventilation, building materials, and ambient environment.
Ethanol is significantly cleaner than biomass fuels, and a larger kitchen significantly improves the quality of household air. Although improved wood stoves with a chimney were effective in reducing concentrations of carbon monoxide in the kitchen, improved charcoal stoves were found to have no significant impact on air quality compared with traditional charcoal stoves. The findings reinforce the need for initiatives that foster fuel switching and improved ventilation as critical first steps to fight unhealthy household air pollution in developing countries.
Indoor Particulate Matter Concentration, Water Boiling Time, and Fuel Use of Selected Alternative Cookstoves in a Home-Like Setting in Rural Nepal
Indoor Particulate Matter Concentration, Water Boiling Time, and Fuel Use of Selected Alternative Cookstoves in a Home-Like Setting in Rural Nepal.
Authors: Kristen D. Ojo, Sutyajeet I. Soneja, et al.
Alternative cookstoves are designed to improve biomass fuel combustion efficiency to reduce the amount of fuel used and lower emission of air pollutants. The Nepal Cookstove Trial (NCT) studies effects of alternative cookstoves on family health. Our study measured indoor particulate matter concentration (PM2.5), boiling time, and fuel use of cookstoves during a water-boiling test in a house-like setting in rural Nepal. Study I was designed to select a stove to be used in the NCT; Study II evaluated stoves used in the NCT. In Study I, mean indoor PM2.5 using wood fuel was 4584 μg/m3, 1657 μg/m3, and 2414 μg/m3 for the traditional, alternative mud brick stove (AMBS-I) and Envirofit G-series, respectively. The AMBS-I reduced PM2.5 concentration but increased boiling time compared to the traditional stove (p-values < 0.001). Unlike AMBS-I, Envirofit G-series did not significantly increase overall fuel consumption.
In Phase II, the manufacturer altered Envirofit stove (MAES) and Nepal Nutrition Intervention Project Sarlahi (NNIPS) altered Envirofit stove (NAES), produced lower mean PM2.5, 1573 μg/m3 and 1341 μg/m3, respectively, relative to AMBS-II 3488 μg/m3 for wood tests. The liquid propane gas stove had the lowest mean PM2.5 concentrations, with measurements indistinguishable from background levels. Results from Study I and II showed significant reduction in PM2.5 for all alternative stoves in a controlled setting. In study I, the AMBS-I stove required more fuel than the traditional stove. In contrast, in study II, the MAES and NAES stoves required statistically less fuel than the AMBS-II.
Reductions and increases in fuel use should be interpreted with caution because the composition of fuels was not standardized—an issue which may have implications for generalizability of other findings as well. Boiling times for alternative stoves in Study I were significantly longer than the traditional stove—a trade-off that may have implications for acceptability of the stoves among end users. These extended cooking times may increase cumulative exposure during cooking events where emission rates are lower; these differences must be carefully considered in the evaluation of alternative stove designs.
The Economics of Household Air Pollution. Annual Review of Resource Economics, July 2015.
Authors: Marc Jeuland, Sanford School of Public Policy and Duke Global Health Institute, Duke University, Durham, NC 27517; email: email@example.com ; Subhrendu K. Pattanayak Sanford School of Public Policy, Duke Global Health Institute, Nicholas School of the Environment, and Department of Economics, Duke University, Durham, North Carolina 27517; email: firstname.lastname@example.org; Randall Bluffstone, Department of Economics, Portland State University, Portland, OR 97207; email: email@example.com
Traditional energy technologies and consumer products contribute to household well-being in diverse ways but also often harm household air quality. We review the problem of household air pollution at a global scale, focusing particularly on the harmful effects of traditional cooking and heating. Drawing on the theory of household production of health, we illustrate the ambiguous relationship between household well-being and adoption of behaviors and technologies that reduce air pollution. We then review how the theory relates to the seemingly contradictory findings emerging from the literature on household demand for clean fuels and stoves. In conclusion, we describe an economics research agenda to close the knowledge gaps so that policies and programs can be designed and evaluated to solve this critical global problem.
Expected final online publication date for the Annual Review of Resource Economics Volume 7 is October 05, 2015. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
Association between wood cooking fuel and maternal hypertension at delivery in central East India. Hypertension in Pregnancy, July 2015.
Authors: Blair J. Wylie, Mrigendra P. Singh, Brent A. Coull, Ashlinn Quinn, Kojo Yeboah-Antwi, Lora Sabin, Davidson H. Hamer, Neeru Singh, and William B. MacLeod
Objective: Smoke from burning of biomass fuels has been linked with adverse pregnancy outcomes and hypertension among nonpregnant subjects; association with hypertension during pregnancy has not been well studied. We evaluated whether the use of wood cooking fuel increases the risk of maternal hypertension at delivery compared to gas which burns with less smoke. Methods: Information on fuel use and blood pressure was available for analysis from a cross-sectional survey of 1369 pregnant women recruited at delivery in India.
Results: Compared to gas users, women using wood as fuel had on average lower mean arterial pressure (adjusted effect size − 2.0 mmHg; 95% CI: −3.77, −0.31) and diastolic blood pressure (adjusted effect size −1.96 mmHg; 95% CI: −3.60, −0.30) at delivery. Risk of hypertension (systolic >139 mmHg or diastolic >89 mmHg) was 14.6% for wood users compared to 19.6% for gas users although this did not reach significance after adjustment, using propensity score techniques, for factors that make wood and gas users distinct (adjusted prevalence ratio 0.76; 95% CI: 0.49, 1.17).
Conclusions: Combustion products from the burning of biomass fuels are similar to those released with tobacco smoking, which has been linked with a reduced risk for preeclampsia. The direction of our findings suggests the possibility of a similar effect for biomass cook smoke. Whether clean cooking interventions being promoted by international advocacy organizations will impact hypertension in pregnancy warrants further analysis as hypertension remains a leading cause of maternal death worldwide and cooking with biomass fuels is widespread.
Lung Function in Rural Guatemalan Women Before and After a Chimney Stove Intervention to Reduce Woodsmoke Exposure
Lung Function in Rural Guatemalan Women Before and After a Chimney Stove Intervention to Reduce Woodsmoke Exposure:Results From RESPIRE and CRECER. Chest, June 2015.
Authors: Michael Guarnieri; Esperanza Diaz; Daniel Pope; Ellen Eisen; Jennifer Mann; Kirk R. Smith; Tone Smith-Sivertsen; Nigel Bruce; John Balmes
Background: Chronic Obstructive Pulmonary Disease (COPD) is the third most frequent cause of death globally with much of this burden attributable to household biomass smoke exposure in developing countries. As biomass smoke exposure is also associated with cardiovascular disease, lower respiratory infection, lung cancer, and cataracts, it presents an important target for public health intervention.
Methods: Lung function in Guatemalan women exposed to woodsmoke from open fires was measured throughout the RESPIRE stove intervention trial, and continued during the CRECER cohort study. In RESPIRE, early stove households received a chimney woodstove at the beginning of the 18-month trial while delayed stove households received a stove at trial completion. Personal exposure to woodsmoke was assessed with exhaled breath carbon monoxide and personal CO tubes. Change in lung function between intervention groups and as a function of woodsmoke exposure was assessed using random effects models.
Results: Of 306 women participating in both studies, acceptable spirometry was collected in 129 early stove and 136 delayed stove households (n=265), with 5.6 years mean follow-up. Despite reduced woodsmoke exposures in early stove households, there were no significant differences in any of the measured spirometric variables during the study period; FEV1, FVC, FEV1/FVC ratio, and annual change, after adjustment for confounding.
Conclusion: In these young Guatemalan women, there was no association between lung function and early randomization to a chimney stove or personal woodsmoke exposure. Future stove intervention trials should incorporate cleaner stoves, longer follow-up, or potentially susceptible groups to identify meaningful differences in lung function.
Biogas: Clean Energy Access with Low-Cost Mitigation of Climate Change, 2015. World Bank.
Authors: E. Somanathan, Randall Bluffstone
This paper finds that the mean reduction in household firewood collection associated with use of a biogas plant for cooking is about 1,100 kilograms per year from a mean of about 2,400 kilograms per year. This estimate is derived by comparing only households with and without biogas in the same village, thus effectively removing the influence of many potential confounders. Further controls for important determinants of firewood collection, such as household size, per capita consumption expenditure, cattle ownership, and unemployment are used to identify the effect of biogas adoption on firewood collection.
Bounds on omitted variable bias are derived with the proportional selection assumption. The central estimate is much smaller than those in the previous literature, but is still large enough for the cost of adopting biogas to be significantly reduced via carbon offsets at a modest carbon price of $10 per ton of CO2e when using central estimates of emission factors and global warming potentials of pollutants taken from the scientific literature.
Use of Systematic Review and Meta-Analysis in Environmental Health Epidemiology: a Systematic Review and Comparison with Guidelines. Current Environmental Health Reports, 2015 :62 DOI: 10.1007/s40572-015-0062-z
Authors: Mary C. Sheehan and Juleen Lam. Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA , Mary C. Sheehan Email: firstname.lastname@example.org
Systematic review (SR) and meta-analysis (MA) have potential to contribute substantially to environmental health (EH) risk assessment and policy-making, provided study questions are clear and methods sound. We undertook a systematic review of the published epidemiological literature for studies using both SR and MA examining associations between chronic low-dose chemical exposures and adverse health outcomes in general populations and compared actual methods and reporting with a checklist based on available published guidelines.
We identified 48 EH SRMAs meeting these criteria. Associations were mainly positive and statistically significant, often involving large populations. A majority of studies followed most general SRMA guidance, although we identified weaknesses in problem formulation, study search, selection and data extraction, and integrating policy implications. Fewer studies followed EH-specific SRMA recommendations, particularly regarding exposure heterogeneity and other risks of bias. Development and adoption of EH-specific SRMA guidelines would contribute to strengthening these tools for public health decision-making.
Children’s personal exposure to air pollution in rural villages in Bhutan. Environmental Research, July 2015.
Authors: Tenzin Wangchuka, Mandana Mazaheri, et al.
This study quantified school children’s daily personal exposure to ultrafine particles (UFP) using real-time monitoring, as well as volatile organic compounds (VOCs) and NO2 using passive sampling in rural Bhutan in order to determine the factors driving the exposures. An activity diary was used to track children’s time activity patterns, and difference in mean exposure levels across sex and indoor/outdoor were investigated with ANOVA. 82 children, attending three primary schools participated in this study; S1 and S2 during the wet season and S3 during the dry season.
Mean daily UFP exposure (cm–3) was 1.08×104 for children attending S1, 9.81×103 for S2, and 4.19×104 for S3. The mean daily NO2 exposure (µg m−3) was 4.27 for S1, 3.33 for S2 and 5.38 for S3 children. Likewise, children attending S3 also experienced higher daily exposure to a majority of the VOCs than those attending S1 and S2. Time-series of UFP personal exposures provided detailed information on identifying sources of these particles and quantifying their contributions to the total daily exposures for each microenvironment.
The highest UFP exposure resulted from cooking/eating, contributing to 64% of the daily exposure, due to firewood combustion in houses using traditional mud cookstoves. The lowest UFP exposures were during the hours that children spent outdoors at school. The outcomes of this study highlight the significant contributions of lifestyle and socio-economic factors in personal exposures and have applications in environmental risk assessment and household air pollution mitigation in Bhutan.
Do improved biomass cookstoves reduce fuelwood consumption and carbon emissions? evidence from rural Ethiopia using a randomized treatment trial with electronic monitoring, 2015. World Bank.
Authors: Beyene, Abebe; Bluffstone, Randy; et al.
This paper uses a randomized experimental design with real-time electronic stove temperature measurements and controlled cooking tests to estimate the fuelwood and carbon dioxide savings from an improved cookstove program in the process of being implemented in rural Ethiopia. Knowing more about how households interact with improved cookstoves is important, because cooking uses a majority of the fuelwood in the country and therefore is an important determinant of greenhouse gas emissions and indoor air pollution.
Creating local networks among stove users generally appears to increase fuelwood savings, and among monetary treatments the most robust positive effects come from free distribution. The paper estimates that on average one improved stove saves approximately 634 kilograms of fuelwood per year or about 0.94 tons of carbon dioxide equivalent per year, which is about half of previous estimates. Using the May 2015 California auction price of $13.39/ton, the carbon sequestration from each stove deployed is worth about $12.59. Such carbon market offset revenues would be sufficient to cover the cost of the stove within one year.
Microgasification cookstoves and pellet fuels from waste biomass: A cost and performance comparison with charcoal and natural gas in Tanzania. African Jnl Sci & Tech, June 2015.
Authors: Don Lotter, Nathan Hunter, Mary Straub, David Msola
Cooking with wood and wood charcoal is done by over 90% of Africa’s population; it has two major challenges: deforestation and indoor air pollution from cooking smoke, the latter being the top risk factor for disease in Tanzania. Microgasification stoves (top lit up draft [TLUD]) that burn pellets produced from agricultural waste have potential to address both of these issues. We examined the relative efficiency and cost of the major urban cooking fuels – charcoal and liquefied natural gas (LNG) – and compared them to cooking with waste biomass-based pellet fuels; we also compared the performance of three models of natural draft (ND) TLUD stove (Troika, Jiko Bomba, St. John’s) and one forced air (fan) stove (Philips).
The Philips and averaged ND stoves used 83 and 133% more pellets by weight respectively to cook beans than charcoal, costing 47 and 93% more at 2013 charcoal and pellet prices. Cooking with LNG costs 387 to 647% more than cooking with charcoal, depending on gas flow rate. The high cost of LNG and LNG stoves will be barriers to the great majority of Tanzanians to move to this improved cookstove technologies (ICTs). Biochar production averaged 59 and 29% of total fuel in the ND and Philips, respectively.
Interviews of 30 ND TLUD stove users showed that 60% abandoned use within one month, 80% stating that they produce too much smoke and 40% stating that controlling the air vent is too much trouble. Seventy five percent said that the TLUD cooks significantly faster than charcoal. Due to the continued 33-99% annual increase in charcoal prices in Tanzania, work on introducing TLUD stoves is justified.
Public health impacts of ecosystem change in the Brazilian Amazon. PNAS, June 2015.
Authors: Simone C. Bauch, Anna M. Birkenbach, Subhrendu K. Pattanayak,1, and Erin O. Sills
The claim that nature delivers health benefits rests on a thin empirical evidence base. Even less evidence exists on how specific conservationpolicies affect multiple health outcomes. We address these gaps in knowledge by combining municipal-level panel data on diseases,public health services, climatic factors, demographics, conservation policies, and other drivers of land-use change in the Brazilian Amazon.
To fully exploit this dataset, we estimate random-effects and quantile regression models of disease incidence. We find that malaria, acute respiratory infection (ARI), and diarrhea incidence are significantly and negatively correlated with the area under strict environmental protection. Results vary by disease for other types of protected areas(PAs), roads, and mining. The relationships between diseases and land-use change drivers also vary by quantile of the disease distribution. Conservation scenarios based on estimated regression results suggest that malaria, ARI, and diarrhea incidence would be reduced by expanding strict PAs, and malaria could be further reduced by restricting roads and mining.
Behavior Change Approaches To Facilitate Clean Cooking and Reduced HAP, 2015. Julia Rosenbaum, WASHplus; FHI 360.
A presentation at the Behavior Change for Clean Cooking: Current Knowledge and Next Steps Seminar, Washington DC, April 2015.
The revolution from the kitchen: Social processes of the removal of traditional cookstoves in Himachal Pradesh, India
The revolution from the kitchen: Social processes of the removal of traditional cookstoves in Himachal Pradesh, India. Energy for Sustainable Development, August 2015.
Authors: Yiting Wang, , Robert Bailis
• We examine social processes of cookstove adoption and displacement in Northern India.
• By subsidizing and reducing logistical barriers, local NGO improved access to LPG.
• Lower caste households remove traditional stoves more readily than higher castes.
• We analyze triggers and drivers propelling changes in kitchen.
• Desire for cleanliness and social identity shape stove choices.
Despite decades of effort, widespread adoption and long-term use of improved cookstoves in developing countries remain hard to achieve. Conventional energy transition models emphasize households’ socio-economic improvement as the most important driver of energy transition. However, previous work has shown households’ continued use of old cookstoves or fuels even when adopting new technologies. Through a case study in India, this paper highlights the socio-political processes of the permanent removal of the traditional chulha cookstove. Newly available liquefied petroleum gas stoves and improved biomass stoves, thought to be substitutes for chulha, lead to different adoption pathways for lower and higher caste households. Lower caste households seem to remove chulha more readily because of sensitivity to chulha’s heavy smoke that pollutes their utensils, kitchen, and clothes. We posit that by adopting cleaner stoves and removing traditional ones, the marginalized can disassociate themselves from practices that perpetuate their social stigma.
The Improved Biomass Stove Saves Wood, But How Often Do People Use It? Evidence from a Randomized Treatment Trial in Ethiopia. World Bank.
Authors: Abebe D. Beyene, Randall Bluffstone, et al.
This paper uses a randomized experimental design and real-time electronic stove use monitors to evaluate the frequency with which villagers use improved biomass-burning Mirt injera cookstoves in rural Ethiopia. Understanding whether, how much, and why improved cookstoves are used is important, because use of the improved stove is a critical determinant of indoor air pollution reductions, and reduced greenhouse gas emissions due to lower fuelwood consumption. Confirming use is, for example, a critical aspect of crediting improved cookstoves’ climate change benefits under the United Nations Reducing Emissions from Deforestation and Forest Degradation Programme.
The paper finds that Ethiopian households in the study area do use the Mirt stove on a regular basis, taking into account regional differences in cooking patterns. In general, stove users also use their Mirt stoves more frequently over time. Giving the Mirt stove away for free and supporting community-level user networks are estimated to lead to more use. The study found no evidence, however, that stove recipients use the stoves more if they have to pay for them, a hypothesis that frequently arises in policy arenas and has also been examined in the literature.