Women exposure to household air pollution after an improved cookstove program in rural San Luis Potosi, Mexico.

The state government of San Luis Potosí (SLP), Mexico implemented an improved cookstove (ICS) program in rural areas. As part of the comprehensive program evaluation, we compared fine particulate material (PM2.5) concentrations in kitchens and patios in treated (TH), and non-treated households (NTH), and analyzed pollutant levels according to patterns of fuels and devices use reported by the women. A panel study was conducted in 728 households (357 TH and 371 NTH) in three regions of SLP including two sampling rounds in 2015-16. Data on exposure determinants, ICS conditions and cooking practices were collected. Daily PM2.5 in kitchen and patio was measured in a subsample. The average treatment effect was estimated using the double difference method. We constructed a mixed linear model to estimate PM2.5 levels for the entire study sample and obtained personal exposure according to time-activity logs. NTH had lower socioeconomic status compared to TH. The average daily PM2.5 concentrations in NTH compared to TH were 155.2 and 92.6 µg/m3 for kitchen and 35.4 and 39.8 µg/m3 for patio, respectively. PM2.5 levels showed significant regional differences but no significant treatment effect. In many cases, the ICS was added to previous open fire and LPG use (stacking). The household size, kitchen ventilation, relative humidity, temperature and the ratio of indoor/outdoor PM2.5 concentration were significant predictors of kitchen PM2.5 levels. The daily PM2.5 personal exposure was significantly reduced using ICS in good conditions or LPG (57 µg/m3) compared to the traditional open fire (86 µg/m3). This study strengthens the evidence on the potential daily PM2.5 exposure reduction for women using an ICS in good conditions or LPG, displacing the polluting open fire. Comprehensive strategies tailored to the sociocultural context of the communities are needed to implement clean energy programs that achieve adoption and sustained use of ICS or LPG.

Fugitive Emissions and Health Implications of Plancha-Type Stoves.

Plancha-type stoves have been widely disseminated in Mexico and Central America, but the contribution of fugitive emissions from these stoves to indoor air concentrations has been poorly quantified. In this study, fugitive emissions were measured for four plancha-type cookstoves most disseminated in Mexico (Patsari, ONIL, Ecostufa, and Mera-Mera). In controlled testing, fugitive emissions from plancha-type chimney stoves ( n = 15 for each stove) were on average 5 ± 3% for PM2.5 and 1 ± 1% for CO, much lower than defaults in WHO Guidelines (25 ± 10%). Using a Monte Carlo single zone model with locally measured parameters, average kitchen concentrations resulting from fugitive emissions were 15 ± 9 µg/m3 for PM2.5 and 0.06 ± 0.04 mg/m3 for CO. On the basis of these models, plancha-type stoves meet benchmarks for WHO Air Quality Guidelines (AQG) Interim Target I for PM2.5 and the 24 h AQG for CO, respectively, with on average 97% of homes meeting the guideline for PM2.5. Similarly, all four plancha-type stoves were ISO IWA Tier 4 for indoor emissions of CO and Tier 3 for indoor emissions of PM2.5. Three-dimensional computational fluid dynamics (CFD) analysis was used to estimate neighborhood pollution impacts of upstream chimney emissions. When chimney emissions were included as background concentrations combined with indoor contributions from fugitive emissions, plancha-type stoves would still meet the WHO AQG Annual Interim Target I for PM2.5 and the 24 h AQG for CO for the scenario modeled in this study.

Children's Respiratory Health After an Efficient Biomass Stove (Patsari) Intervention.

Household use of fuelwood represents a socio-ecological condition with important health effects mainly in rural areas from developing countries. One approach to tackle this problem has been the introduction of efficient wood-burning chimney stoves. The aim of this study was to assess the impact of the introduction of Patsari stoves on the respiratory health of young children in highlands Michoacán, Mexico. A total of 668 households in six rural communities in a fuelwood using region were selected and randomized to receive an improved stove (Patsari) or rely entirely on the traditional wood fire until the end of the follow-up including 10 monthly visits. Adherence to the intervention was variable over the follow-up time. The actual use of the Patsari stove as reported by the mother showed a protective effect mainly on the upper and lower respiratory infection duration (IRR URI 0.79, 95% CI 0.70-0.89, and LRI 0.41, 95% CI 0.21-0.80) compared to households that used only an open fire. Fewer days of child's ill health represents saved time for the woman and avoided disease treatment costs for the family, as well as a decrease in public health costs due to a reduction in the frequency of patient visits.

New approaches to performance testing of improved cookstoves.

Monitoring and evaluation of improved cookstove performance is a critical factor in program success; however, consistent evidence indicates water boiling tests and controlled cooking tests are not representative of stove performance during daily cooking activities, and there is no ability to link these tests to kitchen performance tests during normal daily cooking activities. Since emissions from cookstoves contribute heavily to regional estimates of carbonaceous aerosols and other short-lived greenhouse species and given the current importance of stove performance tests as a basis for global climate prediction models and IPCC inventories, improvements in performance testing are critical to derive more representative estimates. Here real-time combustion efficiencies and emissions rates from daily burn cycles of open fires and improved stoves in Mexico are used to propose a new approach to stove performance testing, using simple and economical measurement methods, based on replication of the distribution of emission rates and combustion efficiencies seen during daily cooking activities in homes. This approach provides more relevant information for global climate models and inventories, while also providing a means to recreate representative emissions profiles in a laboratory setting for technical analyses. On the basis of emission rates and combustion efficiencies during normal daily cooking, we suggest performance criteria that can be used as benchmarks for laboratory testing of improved stoves in the absence of site-specific information, although requiring confirmation by field testing during daily cooking activities.

Ouantification of carbon savings from improved biomass cookstove projects.

In spite of growing interest, a principal obstacle to wider inclusion of improved cookstove projects in carbon trading schemes has been the lack of accountability in estimating CO2-equivalent (CO2-e) savings. To demonstrate that robust estimates of CO2-e savings can be obtained at reasonable cost, an integrated approach of community-based subsampling of traditional and improved stoves in homes to estimate fuel consumption and greenhouse gas emissions, combined with spatially explicit community-based estimates of the fraction of nonrenewable biomass harvesting (fNRB), was used to estimate CO2-e savings for 603 homes with improved Patsari stoves in Purépecha communities of Michoacán, Mexico. Mean annual household CO2-e savings for CO2, CH4, CO, and nonmethane hydrocarbons were 3.9 tCO2-e home(-1) yr(-1) (95% Cl +/- 22%), and for Kyoto gases (CO2 and CH4) were 3.1 tCO2-e home(-1) yr(-1) (95% Cl +/- 26%), respectively, using a weighted mean fNRB harvesting of 39%. CO2-e savings ranged from 1.6 (95% Cl +/- 49%) to 7.5 (95% Cl +/- 17%) tCO2-e home(-1) yr(-1) for renewable and nonrenewable harvesting in individual communities, respectively. Since emission factors, fuel consumption, and fNRB each contribute significantly to the overall uncertainty in estimates of CO2-e savings, community-based assessment of all of these parameters is critical for robust estimates. Reporting overall uncertainty in the CO2-e savings estimates provides a mechanism for valuation of carbon offsets, which would promote better accounting that CO2-e savings had actually been achieved. Cost of CO2-e savings as a result of adoption of Patsari stoves was U.S. $8 per tCO2-e based on initial stove costs, monitoring costs, and conservative stove adoption rates, which is approximately 4 times less expensive than use of carbon capture and storage from coal plants, and approximately 18 times less than solar power. The low relative cost of CO2-e abatement of improved stoves combined with substantial health cobenefits through reduction in indoor air pollution provides a strong rationale for targeting these less expensive carbon mitigation options, while providing substantial economic assistance for stove dissemination efforts.