Evaluating the Performance of Household Liquefied Petroleum Gas Cookstoves

Testing the effectiveness of household fuel conservation strategies: Policy implications for increasing the affordability of exclusive clean cooking

BACKGROUND

Exclusive clean fuel use is essential for realizing health and other benefits but is often unaffordable. Decreasing household-level fuel needs could make exclusive clean fuel use more affordable, but there is a lack of knowledge on the amount of fuel savings that could be achieved through fuel conservation behaviors relevant to rural settings in low- and middle-income countries.

METHODS

Within a trial in Peru, we trained a random half of intervention participants, who had previously received a liquefied petroleum gas (LPG) stove and were purchasing their own fuel, on fuel conservation strategies. We measured the amount of fuel and mega joules (MJ) of energy consumed by all participants, including control participants who were receiving free fuel from the trial. We administered surveys on fuel conservation behaviors and assigned a score based on the number of behaviors performed.

RESULTS

Intervention participants with the training had a slightly higher conservation score than those without (7.2 vs. 6.6 points; p = 0.07). Across all participants, average daily energy consumption decreased by 9.5 MJ for each 1-point increase in conservation score (p < 0.001). Among households who used exclusively LPG (n = 99), each 1-point increase in conservation score was associated with a 0.04 kg decrease in LPG consumption per household per day (p = 0.03). Using pressure cookers and heating water in the sun decreased energy use, while using clay pots and forgetting to close stove knobs increased energy use.

CONCLUSION

Our findings suggest that a household could save 1.16 kg of LPG per month for each additional fuel conservation behavior, for a maximum potential savings of 8.1 kg per month. Fuel conservation messaging could be integrated into national household energy policies to increase the affordability of exclusive clean fuel use, and subsequently achieve the environmental and health benefits that could accompany such a transition.

Climate and health benefits of a transition from gas to electric cooking

Household electrification is thought to be an important part of a carbon-neutral future and could also have additional benefits to adopting households such as improved air quality. However, the effectiveness of specific electrification policies in reducing total emissions and boosting household livelihoods remains a crucial open question in both developed and developing countries. We investigated a transition of more than 750,000 households from gas to electric cookstoves-one of the most popular residential electrification strategies-in Ecuador following a program that promoted induction stoves and assessed its impacts on electricity consumption, greenhouse gas emissions, and health. We estimate that the program resulted in a 5% increase in total residential electricity consumption between 2015 and 2021. By offsetting a commensurate amount of cooking gas combustion, we find that the program likely reduced national greenhouse gas emissions, thanks in part to the country's electricity grid being 80% hydropower in later parts of the time period. Increased induction stove uptake was also associated with declines in all-cause and respiratory-related hospitalizations nationwide. These findings suggest that, when the electricity grid is largely powered by renewables, gas-to-induction cooking transitions represent a promising way of amplifying the health and climate cobenefits of net-carbon-zero policies.

Comprehensive Review on Thermal Performance Enhancement of Domestic Gas Stoves

Cooking is a daily activity in every household, which consumes energy and produces pollution. Using clean gas fuels instead of traditional solid fuels will significantly reduce household air pollution. Although the use of clean-burning burners can reduce emissions, early domestic gas cookers had poor thermal performance. Currently, even small improvements in efficiency can result in significant energy savings due to the large number of domestic gas stoves in use. There has been a long history of research into the development of domestic gas stoves to improve performance and reduce energy consumption. Meanwhile, research into the use of hydrogen-enriched natural gas as a promising environmentally friendly fuel is increasing. In this paper, we perform a descriptive statistics and graphical visualization of network analysis by combining common databases with Bibliometrix. We also analyze the energy balance of domestic gas stoves and the influence of a single factor and multiple factors on stove performance. Then we provide a detailed overview of some research technologies in enhancing the thermal performance of gas stoves. We also discuss the research progress and application prospects for the use of hydrogen-enriched natural gas as a fuel in domestic gas stoves and identify areas for future research and issues that need attention.

Widespread Clean Cooking Fuel Scale-Up and under-5 Lower Respiratory Infection Mortality: An Ecological Analysis in Ecuador, 1990-2019

BACKGROUND

Nationwide household transitions to the use of clean-burning cooking fuels are a promising pathway to reducing under-5 lower respiratory infection (LRI) mortality, the leading cause of child mortality globally, but such transitions are rare and evidence supporting an association between increased clean fuel use and improved health is limited.

OBJECTIVES

This study aimed to investigate the association between increased primary clean cooking fuel use and under-5 LRI mortality in Ecuador between 1990 and 2019.

METHODS

We documented cooking fuel use and cause-coded child mortalities at the canton (county) level in Ecuador from 1990 to 2019 (in four periods, 1988-1992, 1999-2003, 2008-2012, and 2015-2019). We characterized the association between clean fuel use and the rate of under-5 LRI mortalities at the canton level using quasi-Poisson generalized linear and generalized additive models, accounting for potential confounding variables that characterize wealth, urbanization, and child health care and vaccination rates, as well as canton and period fixed effects. We estimated averted under-5 LRI mortalities accrued over 30 y by predicting a counterfactual count of canton-period under-5 LRI mortalities were clean fuel use to not have increased and comparing with predicted canton-period under-5 LRI mortalities from our model and observed data.

RESULTS

From 1990 to 2019, the proportion of households primarily using a clean cooking fuel increased from 59% to 95%, and under-5 LRI mortality fell from 28 to 7 per 100,000 under-5 population. Canton-level clean fuel use was negatively associated with under-5 LRI mortalities in linear and nonlinear models. The nonlinear association suggested a threshold at approximately 60% clean fuel use, above which there was a negative association. Increases in clean fuel use between 1990 and 2019 were associated with an estimated 7,300 averted under-5 LRI mortalities (95% confidence interval: 2,600, 12,100), accounting for nearly 20% of the declines in under-5 LRI mortality observed in Ecuador over the study period.

DISCUSSION

Our findings suggest that the widespread household transition from using biomass to clean-burning fuels for cooking reduced under-5 LRI mortalities in Ecuador over the last 30 y. https://doi.org/10.1289/EHP11016.

CO2 in indoor environments: From environmental and health risk to potential renewable carbon source

In the developed world, individuals spend most of their time indoors. Poor Indoor Air Quality (IAQ) has a wide range of effects on human health. The burden of disease associated with indoor air accounts for millions of premature deaths related to exposure to Indoor Air Pollutants (IAPs). Among them, CO₂ is the most common one, and is commonly used as a metric of IAQ. Indoor CO₂ concentrations can be significantly higher than outdoors due to human metabolism and activities. Even in presence of ventilation, controlling the CO₂ concentration below the Indoor Air Guideline Values (IAGVs) is a challenge, and many indoor environments including schools, offices and transportation exceed the recommended value of 1000 ppm_v. This is often accompanied by high concentration of other pollutants, including bio-effluents such as viruses, and the importance of mitigating the transmission of airborne diseases has been highlighted by the COVID-19 pandemic. On the other hand, the relatively high CO₂ concentration of indoor environments presents a thermodynamic advantage for direct air capture (DAC) in comparison to atmospheric CO₂ concentration. This review aims to describe the issues associated with poor IAQ, and to demonstrate the potential of indoor CO₂ DAC to purify indoor air while generating a renewable carbon stream that can replace conventional carbon sources as a building block for chemical production, contributing to the circular economy.

Heterogeneous changes of chemical compositions, sources and health risks of PM2.5 with the "Clean Heating" policy at urban/suburban/industrial sites

China has enacted the "Clean Heating" (CH) policy in north China. The domain-specific impacts on PM2.5 constituents and sources in small cities are still lacking, which obstruct the further policy optimization. Here, we performed an intensive observation covering the heating period (HP) and pre-heating period (PHP) in winter of 2017 at urban (UR), industrial (IS), and suburban (SUR) sites in one of the "2 + 26" cities. The mean PM2.5 concentrations at UR and IS decreased by 15.2 % and 4.6 %, while increased by 9.8 % at SUR in the HP compared with the PHP, indicating the heterogeneous responses. The lowest contribution percentages of coal combustion (14.6 %) and industrial emissions (17.1 %) to PM2.5 at UR in the HP implied the CH policy played more effective role. The most increase in NO3-/SO42- ratio by 26.8 % and the highest NO3- concentration at UR in the HP were linked mainly with the thermal-NOx emitted from natural gas (NG) burning in view of NOx emission reductions from other sources. The highest concentrations of OC, SO42-, K+, and Cl-, and contribution percentages of biomass burning (20.0 %) and coal combustion (24.8 %) to PM2.5 at SUR in the HP evidenced the enhanced usage of biomass/coal. Coal banning in the HP at IS and UR led to the obvious decreases in OC, SO42-, As, and Sb. Secondary nitrate became the largest PM2.5 source at IS and UR in the HP. Coal banning, emission control on large-size enterprises and ignored control on small-size enterprises efficiently modified the concentrations and health risks of heavy metals. The lowest carcinogenic risks moved from SUR in the PHP to UR in the HP. The policies on de-NOx of NG-burning related enterprises, reduction of biomass/coal usage in suburban area, and strict regulation of small-size enterprises were urgently need to further improve the air quality.

Multinational prediction of household and personal exposure to fine particulate matter (PM2.5) in the PURE cohort study

INTRODUCTION

Use of polluting cooking fuels generates household air pollution (HAP) containing health-damaging levels of fine particulate matter (PM_2.5). Many global epidemiological studies rely on categorical HAP exposure indicators, which are poor surrogates of measured PM_2.5 levels. To quantitatively characterize HAP levels on a large scale, a multinational measurement campaign was leveraged to develop household and personal PM_2.5 exposure models.

METHODS

The Prospective Urban and Rural Epidemiology (PURE)-AIR study included 48-hour monitoring of PM_2.5 kitchen concentrations (n = 2,365) and male and/or female PM_2.5 exposure monitoring (n = 910) in a subset of households in Bangladesh, Chile, China, Colombia, India, Pakistan, Tanzania and Zimbabwe. PURE-AIR measurements were combined with survey data on cooking environment characteristics in hierarchical Bayesian log-linear regression models. Model performance was evaluated using leave-one-out cross validation. Predictive models were applied to survey data from the larger PURE cohort (22,480 households; 33,554 individuals) to quantitatively estimate PM_2.5 exposures.

RESULTS

The final models explained half (R² = 54%) of the variation in kitchen PM_2.5 measurements (root mean square error (RMSE) (log scale):2.22) and personal measurements (R² = 48%; RMSE (log scale):2.08). Primary cooking fuel type, heating fuel type, country and season were highly predictive of PM_2.5 kitchen concentrations. Average national PM_2.5 kitchen concentrations varied nearly 3-fold among households primarily cooking with gas (20 μg/m³ (Chile); 55 μg/m³ (China)) and 12-fold among households primarily cooking with wood (36 μg/m³ (Chile)); 427 μg/m³ (Pakistan)). Average PM_2.5 kitchen concentration, heating fuel type, season and secondhand smoke exposure were significant predictors of personal exposures. Modeled average PM_2.5 female exposures were lower than male exposures in upper-middle/high-income countries (India, China, Colombia, Chile).

CONCLUSION

Using survey data to estimate PM_2.5 exposures on a multinational scale can cost-effectively scale up quantitative HAP measurements for disease burden assessments. The modeled PM_2.5 exposures can be used in future epidemiological studies and inform policies targeting HAP reduction.

Will open waste burning become India's largest air pollution source?

India struggles with frequent exceedances of the ambient air quality standard for particulate matter and benzene. In the past two decades, India has made considerable progress in tackling indoor air pollution, by phasing out kerosene lamps, and pushing biofuel using households towards Liquefied Petroleum Gas (LPG) usage. In this study, we use updated emission inventories and trends in residential fuel consumption, to explore changes in the contribution of different sectors towards India's largest air pollution problem. We find that residential fuel usage is still the largest air pollution source, and that the <10% households using cow dung as cooking fuel contribute ∼50% of the residential PM_2.5 emissions. However, if current trends persist, residential biofuel usage in India is likely to be phased out by 2035. India's renewable energy policies are likely to reduce emissions in the heat and electricity sector, and manufacturing industries, in the mid-term. PM_2.5 emissions from open waste burning, on the other hand, hardly changed in the decade from 2010 to 2020. We conclude that without strong policies to promote recycling and upcycling of non-biodegradable waste, and the conversion of biodegradable waste to biogas, open waste burning is likely to become India's largest source of air pollution by 2035. While our study is limited to India, our findings are of relevance for other countries in the global South suffering from similar waste management challenges.

LPG stove and fuel intervention among pregnant women reduce fine particle air pollution exposures in three countries: Pilot results from the HAPIN trial

The Household Air Pollution Intervention Network trial is a multi-country study on the effects of a liquefied petroleum gas (LPG) stove and fuel distribution intervention on women's and children's health. There is limited data on exposure reductions achieved by switching from solid to clean cooking fuels in rural settings across multiple countries. As formative research in 2017, we recruited pregnant women and characterized the impact of the intervention on personal exposures and kitchen levels of fine particulate matter (PM2.5) in Guatemala, India, and Rwanda. Forty pregnant women were enrolled in each site. We measured cooking area concentrations of and personal exposures to PM2.5 for 24 or 48 h using gravimetric-based PM2.5 samplers at baseline and two follow-ups over two months after delivery of an LPG cookstove and free fuel supply. Mixed models were used to estimate PM2.5 reductions. Median kitchen PM2.5 concentrations were 296 μg/m3 at baseline (interquartile range, IQR: 158-507), 24 μg/m3 at first follow-up (IQR: 18-37), and 23 μg/m3 at second follow-up (IQR: 14-37). Median personal exposures to PM2.5 were 134 μg/m3 at baseline (IQR: 71-224), 35 μg/m3 at first follow-up (IQR: 23-51), and 32 μg/m3 at second follow-up (IQR: 23-47). Overall, the LPG intervention was associated with a 92% (95% confidence interval (CI): 90-94%) reduction in kitchen PM2.5 concentrations and a 74% (95% CI: 70-79%) reduction in personal PM2.5 exposures. Results were similar for each site. CONCLUSIONS: The intervention was associated with substantial reductions in kitchen and personal PM2.5 overall and in all sites. Results suggest LPG interventions in these rural settings may lower exposures to the WHO annual interim target-1 of 35 μg/m3. The range of exposure contrasts falls on steep sections of estimated exposure-response curves for birthweight, blood pressure, and acute lower respiratory infections, implying potentially important health benefits when transitioning from solid fuels to LPG.

A critical review of pollutant emission factors from fuel combustion in home stoves

A large population does not have access to modern household energy and relies on solid fuels such as coal and biomass fuels. Burning of these solid fuels in low-efficiency home stoves produces high amounts of multiple air pollutants, causing severe air pollution and adverse health outcomes. In evaluating impacts on human health and climate, it is critical to understand the formation and emission processes of air pollutants from these combustion sources. Air pollutant emission factors (EFs) from indoor solid fuel combustion usually highly vary among different testing protocols, fuel-stove systems, sampling and analysis instruments, and environmental conditions. In this critical review, we focus on the latest developments in pollutant emission factor studies, with emphases on the difference between lab and field studies, fugitive emission quantification, and factors that contribute to variabilities in EFs. Field studies are expected to provide more realistic EFs for emission inventories since lab studies typically do not simulate real-world burning conditions well. However, the latter has considerable advantages in evaluating formation mechanisms and variational influencing factors in observed pollutant EFs. One main challenge in field emission measurement is the suitable emission sampling system. Reasons for the field and lab differences have yet to be fully elucidated, and operator behavior can have a significant impact on such differences. Fuel properties and stove designs affect emissions, and the variations are complexly affected by several factors. Stove classification is a challenge in the comparison of EF results from different studies. Lab- and field-based methods for quantifying fugitive emissions, as an important contributor to indoor air pollution, have been developed, and priority work is to develop a database covering different fuel-stove combinations. Studies on the dynamics of the combustion process and evolution of air pollutant formation and emissions are scarce, and these factors should be an important aspect of future work.

Cookstove Emissions and Performance Evaluation Using a New ISO Protocol and Comparison of Results with Previous Test Protocols

In 2018, the International Organization for Standardization (ISO) 19867-1 "Harmonized laboratory test protocols" were released for establishing improved quality and comparability for data on cookstove air pollutant emissions, efficiency, safety, and durability. This is the first study that compares emissions [carbon dioxide, carbon monoxide, total hydrocarbons, methane, nitrogen oxides, fine particulate matter (PM_2.5), organic carbon, elemental carbon, and ultrafine particles] and efficiency data between the ISO protocol and the Water Boiling Test (WBT). The study examines six stove/fuel combinations [liquefied petroleum gas (LPG), pellet, wood fan, wood rocket, three stone fire, and charcoal] tested in the same US EPA laboratory. Evaluation of the ISO protocol shows improvements over previous test protocols and that results are relatively consistent with former WBT data in terms of tier ratings for emissions and efficiency, as defined by the ISO 19867-3 "Voluntary Performance Targets." Most stove types remain similarly ranked using ISO and WBT protocols, except charcoal and LPG are in higher PM_2.5 tiers with the ISO protocol. Additionally, emissions data including polycyclic aromatic hydrocarbons are utilized to compare between the ISO and Firepower Sweep Test (FST) protocols. Compared to the FST, the ISO protocol results in generally higher PM_2.5 tier ratings.

A cluster randomised trial of cookstove interventions to improve infant health in Ghana

Introduction

Household air pollution from solid fuel combustion for cooking and heating is a leading cause of childhood morbidity and mortality worldwide. We hypothesised that clean cooking interventions delivered during pregnancy would improve child health.

Methods

We conducted a cluster randomised trial in rural Ghana to test whether providing pregnant women liquefied petroleum gas (LPG) cookstoves or improved biomass cookstoves would reduce personal carbon monoxide and fine particulate pollution exposure, increase birth weight and reduce physician-assessed severe pneumonia in the first 12 months of life, compared with control participants who continued to cook with traditional stoves. Primary analyses were intention-to-treat. The trial was registered with ClinicalTrials.gov and follow-up is complete.

Results

Enrolment began on 14 April 2014, and ended on 20 August 2015. We enrolled 1414 pregnant women; 361 in the LPG arm, 527 in the improved biomass cookstove arm and 526 controls. We saw no improvement in birth weight (the difference in mean birth weight for LPG arm births was 29 g lighter (95% CI −113 to 56, p=0.51) and for improved biomass arm births was 9 g heavier (95% CI −64 to 82, p=0.81), compared with control newborns) nor severe child pneumonia (the rate ratio for pneumonia in the LPG arm was 0.98 (95% CI 0.58 to 1.70; p=0.95) and for the improved biomass arm was 1.21 (95% CI 0.78 to 1.90; p=0.52), compared with the control arm). Air pollution exposures in the LPG arm remained above WHO health-based targets (LPG median particulate matter less than 2.5 microns in diameter (PM_2.5) 45 µg/m³; IQR 32–65 vs control median PM_2.5 67 µg/m³, IQR 46–97).

Conclusions

Neither prenatally-introduced LPG nor improved biomass cookstoves improved birth weight or reduced severe pneumonia risk in the first 12 months of life. We hypothesise that this is due to lower-than-expected exposure reductions in the intervention arms.

Trial registration number

NCT01335490.

The climate and health benefits from intensive building energy efficiency improvements

Intensive building energy efficiency improvements can reduce emissions from energy use, improving outdoor air quality and human health, but may also affect ventilation and indoor air quality. This study examines the effects of highly ambitious, yet feasible, building energy efficiency upgrades in the United States. Our energy efficiency scenarios, derived from the literature, lead to a 6 to 11% reduction in carbon dioxide emissions and 18 to 25% reductions in particulate matter (PM2.5) emissions in 2050. These reductions are complementary with a carbon pricing policy on electricity. However, our results also point to the importance of mitigating indoor PM2.5 emissions, improving PM2.5 filtration, and evaluating ventilation-related policies. Even with no further ventilation improvements, we estimate that intensive energy efficiency scenarios could prevent 1800 to 3600 premature deaths per year across the United States in 2050. With further investments in indoor air quality, this can rise to 2900 to 5100.

Towards Sustainable Development Goal 7 “Universal Access to Clean Modern Energy”: National Strategy in Rwanda to Scale Clean Cooking with Bottled Gas

More than 90% of Rwandans rely on polluting solid fuels to meet their cooking needs. The negative impacts on health, climate, and the environment have led the Rwandan government to set a target of halving that number to 42% by 2024. A National Master Plan to promote scale up of liquefied petroleum gas (LPG) has been developed to define (i) the necessary market conditions, (ii) public and private sector interventions, and (iii) the expected societal impacts. Findings are reported from modelling scenarios of scaling LPG use towards the 2024 policy target and the 2030 target for “universal access to clean modern energy” (SDG7). Household LPG use is projected to increase from 5.6% in 2020 to 13.2% by 2024 and 38.5% by 2030. This level of adoption could result in a reduction of 7656 premature deaths and 403,664 disability-adjusted-life-years (DALYs), as well as 243 million trees saved. Reductions in carbon dioxide and black carbon emissions equivalents (CO2e and BCe, respectively) are estimated to reach 25.6 million MT and 14.9 MT, respectively, by 2030. While aggressive policy intervention is required, the health, environmental, and developmental benefits are clear. Implementation of the Rwanda National LPG Master Plan will provide a model for other sub-Saharan African countries to address the priorities for cessation of reliance on solid fuels as an energy source.

COVID-19 impacts on household energy & food security in a Kenyan informal settlement: The need for integrated approaches to the SDGs

This longitudinal study presents the joint effects of a COVID-19 community lockdown on household energy and food security in an informal settlement in Nairobi, Kenya. Randomly administered surveys were completed from December 2019-March 2020 before community lockdown (n = 474) and repeated in April 2020 during lockdown (n = 194). Nearly universal (95%) income decline occurred during the lockdown and led to 88% of households reporting food insecurity. During lockdown, a quarter of households (n = 17) using liquefied petroleum gas (LPG), a cleaner cooking fuel typically available in pre-set quantities (e.g. 6 kg cylinders), switched to polluting cooking fuels (kerosene, wood), which could be purchased in smaller amounts or gathered for free. Household size increases during lockdown also led to participants' altering their cooking fuel, and changing their cooking behaviors and foods consumed. Further, households more likely to switch away from LPG had lower consumption prior to lockdown and had suffered greater income loss, compared with households that continued to use LPG. Thus, inequities in clean cooking fuel access may have been exacerbated by COVID-19 lockdown. These findings demonstrate the complex relationship between household demographics, financial strain, diet and cooking patterns, and present the opportunity for a food-energy nexus approach to address multiple Sustainable Development Goals (SDGs): achieving zero hunger (SDG 2) and universal affordable, modern and clean energy access (SDG 7) by 2030. Ensuring that LPG is affordable, accessible and meets the dietary and cooking needs of families should be a policy priority for helping improve food and energy security among the urban poor.

COVID-19 impacts on household energy & food security in a Kenyan informal settlement: The need for integrated approaches to the SDGs

This longitudinal study presents the joint effects of a COVID-19 community lockdown on household energy and food security in an informal settlement in Nairobi, Kenya. Randomly administered surveys were completed from December 2019-March 2020 before community lockdown (n = 474) and repeated in April 2020 during lockdown (n = 194). Nearly universal (95%) income decline occurred during the lockdown and led to 88% of households reporting food insecurity. During lockdown, a quarter of households (n = 17) using liquefied petroleum gas (LPG), a cleaner cooking fuel typically available in pre-set quantities (e.g. 6 kg cylinders), switched to polluting cooking fuels (kerosene, wood), which could be purchased in smaller amounts or gathered for free. Household size increases during lockdown also led to participants' altering their cooking fuel, and changing their cooking behaviors and foods consumed. Further, households more likely to switch away from LPG had lower consumption prior to lockdown and had suffered greater income loss, compared with households that continued to use LPG. Thus, inequities in clean cooking fuel access may have been exacerbated by COVID-19 lockdown. These findings demonstrate the complex relationship between household demographics, financial strain, diet and cooking patterns, and present the opportunity for a food-energy nexus approach to address multiple Sustainable Development Goals (SDGs): achieving zero hunger (SDG 2) and universal affordable, modern and clean energy access (SDG 7) by 2030. Ensuring that LPG is affordable, accessible and meets the dietary and cooking needs of families should be a policy priority for helping improve food and energy security among the urban poor.

Transition to clean household energy through an application of integrated model: Ensuring sustainability for better health, climate and environment

Sustained use and adoption of clean cooking fuels have become an important concern for developing countries due to the enormous burden of diseases attributable to household air pollution (HAP). The transition and adoption of clean household energy involve various socio-economic, behavioral, and technological barriers at different community levels. Hence, the present paper aims to scrutinize the factors, key determinants, and other interventions among rural households that limit clean cookstoves' sustained uses. The study proposes an integrated model to enhance clean cooking fuel uptake and uses based on the available evidence. The health, climate and environmental factors were identified as the key to trigger the adoption of clean cooking fuel alternatives. The model comprises the integration of components for targeted clean fuel policy interventions and promotes green recovery. The elements include Knowledge, Housing characteristics, Awareness, Interventions, Willingness to pay, Adoption, Lower emissions and Gender Equality (THE KHAIWAL model) to ascertain the intervention focus regions. Integration of model components in policy implementation will promote clean household energy to reduce emissions, leading to improve quality of life, good health, women empowerment, better air quality and climate.

In-use emissions from biomass and LPG stoves measured during a large, multi-year cookstove intervention study in rural India

We conducted an emission measurement campaign as a part of a multiyear cookstove intervention trial in two rural locations in northern and southern India. 253 uncontrolled cooking tests measured emissions in control and intervention households during three ~3-month-long measurement periods in each location. We measured pollutants including fine particulate matter (PM_2.5), organic and elemental carbon (OC, EC), black carbon (BC) and carbon monoxide (CO) from stoves ranging from traditional solid fuel (TSF) to improved biomass stoves (rocket, gasifier) to liquefied petroleum gas (LPG) models. TSF stoves showed substantial variability in pollutant emission factors (EFs; g kg^-1 wood) and optical properties across measurement periods. Multilinear regression modeling found that measurement period, fuel properties, relative humidity, and cooking duration are significant predictors of TSF EFs. A rocket stove showed moderate reductions relative to TSF. LPG stoves had the lowest pollutant EFs, with mean PM_2.5 and CO EFs (g MJ_delivered^-1) >90% lower than biomass stoves. However, in-home EFs of LPG were substantially higher than lab EFs, likely influenced by non-ideal combustion performance, emissions from food and possible influence from other combustion sources. In-home emission measurements may depict the actual exposure benefits associated with dissemination of LPG stoves in real world interventions.

Fuel Aromaticity Promotes Low-Temperature Nucleation Processes of Elemental Carbon from Biomass and Coal Combustion

Significant elemental carbon (EC) emissions from low-temperature solid fuel combustion cannot be explained by classical mechanisms ascribing EC to higher-temperature condensation (> 850 °C). The importance of fuel composition in promoting EC nucleation was investigated by studying EC and polycyclic aromatic hydrocarbon (PAH) formation at multiple-ignition temperatures (300-900 °C) using fuels with different aromatic contents (i.e., straw, wood, and coal). Biomass and coal combustion at 300 °C can produce substantial EC containing a large amount of soot-EC, a known high-temperature condensation product, possibly because aromatics reduce EC nucleation barriers, corresponding to the increasing ratios of soot-EC to char-EC from straw to coal (1.22 to 3.61). High- to low-molecular-weight PAH ratios in biomass combustion were four times lower than those in coal combustion, resulting in different EC formation atmospheres. Specifically, 31.4% of PAHs from biomass combustion were indene, compared to only 0.24% for coal, indicating that resonance-stabilized hydrocarbon-radical chain reactions dominated EC nucleation in biomass combustion. Five- to six-membered PAH ratios were always higher than one in biomass combustion but increased significantly from 0.5 to 2 with increasing temperature in coal combustion, indicating that PAHs generated through aromatic decomposition in coal could form EC through van-der-Waals forces and phenyl addition/cyclization-based covalent bonding at low and high temperatures, respectively.

Quantifying source contributions for indoor CO2 and gas pollutants based on the highly resolved sensor data

Household air pollution is the dominant contributor to population air pollutant exposure, but it is often of less concern compared with ambient air pollution. One of the major knowledge gaps in this field are detailed quantitative source contributions of indoor pollutants, especially for gaseous compounds. In this study, temporally, spatially, and vertically resolved monitoring for typical indoor gases including CO₂, CO, formaldehyde, methane, and the total volatile organic compounds (VOCs) was conducted to address pollution dynamics and major sources in an urban apartment. The indoor concentrations were significantly higher than the simultaneously measured outdoor concentrations. A new statistic approach was proposed to quantitatively estimate contributions of different sources. It was estimated that outdoor CO₂ contributed largely to the indoor CO₂, while main indoor sources were human metabolism and cooking. Outdoor infiltration and cooking contributed almost equally to the indoor CO. The contribution of outdoor infiltration to methane was much higher than that to formaldehyde. Cooking contributed to 24%, 19%, and 25% of indoor formaldehyde, methane, and VOCs, whereas the other unresolved indoor sources contributed 61%, 19%, and 35% of these pollutants, respectively. Vertical measurements showed that the uplifting of hot air masses led to relatively high concentrations of the pollutants in the upper layer of the kitchen and in the other rooms to a lesser extent.

Evaluation of emission indices and air quality implications of liquefied petroleum gas burners

Major cities in Nigeria has adopted the use of liquefied petroleum gas (LPG) as their main source for domestic cooking, however, this adoption led to different designs of LPG burners in Nigeria market. The emission indices of these burners and their air quality implications are yet to be ascertain. To solve these problems and fill the data gap, laboratory analysis were carried out on 16 conventional LPG burner heads identified in Nigeria market. The emission factors for Carbon monoxide (CO), Oxide of Nitrogen (NOx), Carbon dioxide (CO₂), Hydrocarbons (HC) and sulphur dioxide (SO₂) on the basis of useful energy delivered were 0.123–21.784 g/MJ_d, 1.973–32.943 g/MJ_d, 73.819–147.639 g/MJ_d, 4.069–171.643 g/MJ_d and 0–0.1644 g/MJ_d while the emission rates were 0.000238–0.1125 g/s, 0.0071–0.2 g/s, 0.1083–0.7 g/s, 0.0117–1.2583 g/s and 0–0.000194 g/s respectively. It was observed that results from the study were within the International Organization for Standardization, International Workshop Agreement 11 and World Health Organization indoor air quality guidelines for human protection.

Health and Climate Impacts of Scaling Adoption of Liquefied Petroleum Gas (LPG) for Clean Household Cooking in Cameroon: A Modeling Study

BACKGROUND

The Cameroon government has set a target that, by 2030, 58% of the population will be using Liquefied Petroleum Gas (LPG) as a cooking fuel, in comparison with less than 20% in 2014. The National LPG Master Plan (Master Plan) was developed for scaling up the LPG sector to achieve this target.

OBJECTIVES

This study aimed to estimate the potential impacts of this planned LPG expansion (the Master Plan) on population health and climate change mitigation, assuming primary, sustained use of LPG for daily cooking.

METHODS

We applied existing and developed new mathematical models to calculate the health and climate impacts of expanding LPG primary adoption for household cooking in Cameroon over two periods: a) short-term (2017-2030): Comparing the Master Plan 58% target with a counterfactual LPG adoption of 32% in 2030, in line with current trends; and b) long-term (2031-2100, climate modeling only), assuming Cameroon will become a mature and saturated LPG market by 2100 (73% adoption, based on Latin American countries). We compared this with a counterfactual adoption of 41% by 2100, in line with current trends.

RESULTS

By 2030, successful implementation of the Master Plan was estimated to avert about 28,000 (minimum = 22,000 , maximum = 35,000 ) deaths and 770,000 (minimum = 580,000 maximum = 1   million ) disability-adjusted life years. For the same period, we estimated reductions in pollutant emissions of more than a third in comparison with the counterfactual, leading to a global cooling of - 0.1   milli   ° C in 2030. For 2100, a cooling impact from the Master Plan leading to market saturation (73%) was estimated to be - 0.70   milli   ° C in comparison with to the counterfactual, with a range of - 0.64 to - 0.93   milli   ° C based on different fractions of nonrenewable biomass.

DISCUSSION

Successful implementation of the Master Plan could have significant positive impacts on population health in Cameroon with no adverse impacts on climate. https://doi.org/10.1289/EHP4899.

Direct combustion of waste oil in domestic stove by an internal heat re-circulation atomization technology: Emission and performance analysis

Direct use of waste oil as fuel to meet the residential energy demands, is very attractive due to its potentials to decrease fossil fuel consumption, reduce pollution and increase sustainability. This paper uses a domestic stove with an internal heat re-circulation and self-atomization technology to burn yellow waste cooking oil (WCO-1), brown waste cooking oil (WCO-2) and waste lubricant oil (WLO). Emission factors (EFs), energy efficiency and modified combustion efficiency (MCE) of this combined fuel/stove system were determined under space-heating and cooking modes. The results showed that EFs of CO, PM_2.5, total 16 PAHs and corresponding toxic equivalent quantity (TEQ) values ranged from 2.18 × 10³ to 4.90 × 10³ mg/MJ_net, 16.36-69.40 mg/MJ_net, 2.39-12.93 μg/MJ_net and 0.16-0.92 μg of TEQ/MJ_net. WCO-1 was verified to be the cleanest fuel with the highest energy efficiency (85.3 ± 3.3% and 90.4 ± 2.2%) and lowest emission levels, such as NO (53.75 ± 2.62 and 37.09 ± 5.41 mg/MJ_net), NO₂ (82.40 ± 3.96 and 56.87 ± 8.29 mg/MJ_net) and PM_2.5 (20.94 ± 6.55 and 16.35 ± 5.06 mg/MJ_net) compared to WCO-2 and WLO. The estimated total cost of using waste oil for each household in winter was much cheaper than some current available clean energy means, including only USD$ 400 of stove price and USD$ 250/ton of fuel per year. It is a promising candidate choice for replacing low-quality solid fuels in rural China and 2.62 million rural households would achieve environmental and economic benefits if promoting direct combustion of waste oil for daily heating and cooking.

Supply Considerations for Scaling Up Clean Cooking Fuels for Household Energy in Low- and Middle-Income Countries

Promoting access to clean household cooking energy is an important subject for policy making in low- and middle-income countries, in light of urgent and global efforts to achieve universal energy access by 2030 (Sustainable Development Goal 7). In 2014, the World Health Organization issued "Guidelines for Indoor Air Quality: Household Fuel Combustion", which recommended a shift to cleaner fuels rather than promotion of technologies that more efficiently combust solid fuels. This study fills an important gap in the literature on transitions to household use of clean cooking energy by reviewing supply chain considerations for clean fuel options in low- and middle-income countries. For the purpose of this study, we consider electricity, liquefied petroleum gas (LPG), alcohol fuels, biogas, and compressed biomass pellets burned in high performing gasifier stoves to be clean fuel options. Each of the clean fuels reviewed in this study, as well as the supply of electricity, presents both constraints and opportunities for enhanced production, supply, delivery, and long-term sustainability and scalability in resource-poor settings. These options are reviewed and discussed together with policy and regulatory considerations to help in making these fuel and energy choices available and affordable. Our hope is that researchers, government officials and policy makers, and development agencies and investors will be aided by our comparative analysis of these clean household energy choices.

Household Transitions to Clean Energy in a Multi-Provincial Cohort Study in China

Household solid fuel (biomass, coal) burning contributes to climate change and is a leading health risk factor. How and why households stop using solid fuel stoves after adopting clean fuels has not been studied. We assessed trends in the uptake, use, and suspension of household stoves and fuels in a multi-provincial cohort study of 753 Chinese adults and evaluated determinants of clean fuel uptake and solid fuel suspension. Over one-third (35%) and one-fifth (17%) of participants suspended use of solid fuel for cooking and heating, respectively, during the past 20 years. Determinants of solid fuel suspension (younger age, widowed) and of earlier suspension (younger age, higher education, and poor self-reported health status) differed from the determinants of clean fuel uptake (younger age, higher income, smaller households, and retired) and of earlier adoption (higher income). Clean fuel adoption and solid fuel suspension warrant joint consideration as indicators of household energy transition. Household energy research and planning efforts that more closely examine solid fuel suspension may accelerate household energy transitions that benefit climate and human health.

In-Field Emission Measurements from Biogas and Liquified Petroleum Gas (LPG) Stoves

Household air pollution from solid fuel cooking causes millions of deaths each year and contributes to climate change. These emissions can be reduced if households transition to cleaner cooking fuels such as LPG or biogas, yet emission measurements during actual use are limited. Six LPG and 57 biogas cooking event emissions were measured during typical cooking practices in Nepal. Emission factors are reported for elemental carbon (EC), organic carbon (OC), particulate matter (PM 2.5 ), and carbon monoxide (CO) and compared to measurements from wood stoves in the same households. Biogas cooking emission factors were 7.4 ± 10.9 mg MJ − 1 for PM 2.5 and 0.2 ± 0.3 mg MJ − 1 for EC on a fuel energy basis, and were not significantly different from LPG stoves (9.5 ± 6.8 mg MJ − 1 for PM 2.5 and 0.3 ± 0.3 mg MJ − 1 for EC, p > 0.05). Wood stoves emitted 50 times more PM 2.5 than biogas on a fuel energy basis and 230 times more EC. EC emissions were about 3% of total particle emissions from biogas and LPG stoves. Most PM 2.5 emissions from gas stoves were attributed to food frying and stove ignition (90%), not the gas fuel (10%), implying that there is a limit to emission reductions that can be achieved with improved fuels.

Cooking/Window Opening and Associated Increases of Indoor PM2.5 and NO2 Concentrations of Children’s Houses in Kaohsiung, Taiwan

High concentrations of air pollutants and increased morbidity and mortality rates are found in industrial areas, especially for the susceptible group, children; however, most studies use atmospheric dispersion modeling to estimate household air pollutants. Therefore, the aim of this study was to assess the indoor air quality, e.g., CO, CO2, NO2, SO2, O3, particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5), and their influence factors in children’s homes in an industrial city. Children in the “general school”, “traffic school”, and “industrial school” were randomly and proportionally selected. Air pollutants were sampled for 24 h in the living rooms and on the balcony of their houses and questionnaires of time–microenvironment–activity-diary were recorded. The indoor CO concentration of the traffic area was significantly higher than that of the industrial area and the general area. In regard to the effects of window opening, household NO2 and PM2.5 concentrations during window opening periods were significantly higher than of the reference periods. For the influence of cooking, indoor CO2, NO2, and PM2.5 levels during the cooking periods were significantly higher than that of the reference periods. The indoor air quality of children in industrial cities were affected by residential areas and household activities.

Effectiveness of a Household Energy Package in Improving Indoor Air Quality and Reducing Personal Exposures in Rural China

We evaluated whether an energy package comprising a low-polluting semigasifier cookstove with chimney, water heater, and pelletized biomass fuel would improve air pollution in China. We measured the stove use, 48-h air pollution exposures (PM_2.5, black carbon), and kitchen concentrations (PM_2.5, black carbon, carbon monoxide, nitrogen oxides) for 205 women, along with ambient PM_2.5. Over half (n = 125) were offered the energy package after baseline assessment, forming "treated" and "untreated" groups, and we repeated the measurements up to 3 occasions over 18-months. Kitchen carbon monoxide did not change, and nitrogen oxides increased in summer but decreased in winter for both groups. Summer geometric mean exposures and kitchen concentrations of PM_2.5 and black carbon decreased by 24-67% in women who received the energy package, but greater reductions (48-70%) were observed in untreated homes, likely due to increased use of gas stoves. After adjusting for differences in outdoor PM_2.5, receiving the energy package was associated with decreased winter exposures to PM_2.5 (-46%; 95% CI: -70, -2) and black carbon (-55%; -74, -25) and the summer increases were smaller (PM_2.5: 8%; -22, 51 and black carbon: 37%; -12, 113). However, PM_2.5 exposures remained 1.5-3 times higher than those of health-based international air pollution targets.

In-Home Emissions Performance of Cookstoves in Asia and Africa

This paper presents results from eight field studies in Asia and Africa on the emissions performance of 16 stove/fuel combinations measured during normal cooking events in homes. Characterizing real-world emissions performance is important for understanding the climate and health implications of technologies being promoted as alternatives to displace baseline cooking stoves and fuels. Almost all of the stove interventions were measured to have substantial reductions in PM2.5 and CO emissions compared to their respective baseline technologies (reductions of 24–87% and 25–80%, for PM2.5 and CO emission rates, respectively), though comparison with performance guidance from the World Health Organization (WHO) and the International Organization for Standardization (ISO) suggests that further improvement for biomass stoves would help realize more health benefits. The emissions of LPG stoves were generally below the WHO interim PM2.5 emissions target (1.75 mg/min) though it was not clear how close they were to the most aspirational ISO (0.2 mg/min) or WHO (0.23 mg/min) targets as our limit of detection was 1.1 mg/min. Elemental and organic carbon emission factors and elemental-to-total carbon ratios (medians ranging from 0.11 to 0.42) were in line with previously reported field-based estimates for similar stove/fuel combinations. Two of the better performing forced draft stoves used with pellets—the Oorja (median ET/TC = 0.12) and Eco-Chula (median ET/TC = 0.42)—were at opposite ends of the range, indicating that important differences in combustion conditions can arise even between similar stove/fuel combinations. Field-based tests of stove performance also provide important feedback for laboratory test protocols. Comparison of these results to previously published water boiling test data from the laboratory reinforce the trend that stove performance is generally better during controlled laboratory conditions, with modified combustion efficiency (MCE) being consistently lower in the field for respective stove/fuel categories. New testing approaches, which operate stoves through a broader range of conditions, indicate potential for better MCE agreement than previous versions of water boiling tests. This improved agreement suggests that stove performance estimates from a new ISO laboratory testing protocol, including testing stoves across low, medium, and high firepower, may provide more representative estimates of real-world performance than previously used tests. More representative results from standardized laboratory testing should help push stove designs toward better real-world performance as well as provide a better indication of how the tested technologies will perform for the user.

Fluctuation in time-resolved PM2.5 from rural households with solid fuel-associated internal emission sources

Indoor air contributes significantly to overall exposure, particularly for rural Chinese who often use solid fuels for cooking and/or heating. Unfortunately, overlooked rural indoor air leads to a critical knowledge gap. Simultaneous measurements in the kitchen, living room, and immediately outside of houses using six-channel particle counters were carried out in 18 biomass-burning rural and 3 non-biomass-burning urban households (as a comparison) in winter to characterize dynamic change patterns indoor air pollution and indoor-outdoor relationship. The rural households mainly used wood or crop residues for cooking and heating, while the urban households used pipelined natural gas for cooking and air conditioners for heating. In rural households with significant solid-fuel burning internal sources, the highest concentration was found in the kitchen (101 ± 56 μg/m³), with comparable levels in the living room (99 ± 46 μg/m³) and low levels in outdoor air (91 ± 39 μg/m³). A generally opposite direction of indoor-outdoor exchange was found between the rural and urban households. PM in kitchen air is smaller than that in living rooms and outdoors because solid fuel burning (mainly in rural households) and cooking oil heating (in rural and urban households). Indoor and outdoor PM concentration changed synchronously, with a slight delay in indoor air in urban households but a slight delay in outdoor air in rural households. Cooking, heating, and smoking elevated indoor PM significantly, but different from the cooking activity that produced peaks lasting for about 30 min, emissions from heating created a series of peaks due to frequent disturbance and fuel-feeding and had more significant impacts on the daily average concentration. Distinct indoor-outdoor relationships and dynamic change patterns between the two household categories w/o strong internal biomass burning sources imply that totally different model schemes are needed to quantitatively address indoor air pollution and inhalation exposure.

Field-based emission measurements of biomass burning in typical Chinese built-in-place stoves

Residential combustion emission contributes significantly to ambient and indoor air pollution in China; however, this pollution source is poorly characterized and often overlooked in national pollution control policies. Few studies, and even fewer field-based investigations, have evaluated pollutant emissions from indoor biomass burning. One significant feature of Chinese household biofuel stoves is that many are built on site. In this study, 112 tests were conducted to investigate pollutant emission factors and variations for 11 fuel-stove combinations in actual use in the field. Results showed that, compared to those emission tests under controlled fuel burning conditions, EFs of methane, sulfur dioxide, particulate matter, and organic carbon from the field-based uncontrolled tests were higher, but carbon monoxide, nitrogen oxides, and elemental carbon were not significantly different. Controlled burning tests may be unrepresentative of real-world fuel burning. Pollutant emissions from uncontrolled burning tests had much higher variations compared with controlled tests. Most pollutant emissions from indoor straw burning are higher than that in open burning, except nitrogen oxides. The typical built-in-place home stoves in China had low efficiencies and high pollutant emissions that were rated as Tier 0 (the worst) or Tier 1 of a four-tier scale according to the International Organization for Standardization, International Workshop Agreement 11-2012. Effective interventions are expected to lower pollutant emissions from residential combustion to improve air quality and to protect human health.

An analysis of efforts to scale up clean household energy for cooking around the world

Approximately 3 billion people, most of whom live in Asia, Africa, and the Americas, rely on solid fuels (i.e. wood, crop wastes, dung, charcoal) and kerosene for their cooking needs. Exposure to household air pollution from burning these fuels is estimated to account for approximately 3 million premature deaths a year. Cleaner fuels - such as liquefied petroleum gas, biogas, electricity, and certain compressed biomass fuels - have the potential to alleviate much of this significant health burden. A wide variety of clean cooking intervention programs are being implemented around the world, but very few of these efforts have been analyzed to enable global learning. The Clean Cooking Implementation Science Network (ISN), supported by the U.S. National Institutes of Health (NIH) and partners, identified the need to augment the publicly available literature concerning what has worked well and in what context. The ISN has supported the development of a systematic set of case studies, contained in this Special Issue, examining clean cooking program rollouts in a variety of low- and middle-income settings around the world. We used the RE-AIM (reach, effectiveness, adaptation, implementation, maintenance) framework to coordinate and evaluate the case studies. This paper describes the clean cooking case studies project, introduces the individual studies contained herein, and proposes a general conceptual model to support future planning and evaluation of household energy programs.

The Mega Conversion Program from Kerosene to LPG in Indonesia: lessons learned and recommendations for future clean cooking energy expansion

BACKGROUND

In 2007, the Indonesian Government instigated a national program to convert domestic kerosene users to liquefied petroleum gas (LPG) for cooking. This was primarily motivated by the rising cost of kerosene subsidies.

OBJECTIVE

To review the national conversion program and LPG scale up by evaluating its impacts, including assessing sustained changes in cooking behaviour and consequent reductions in exposure to household air pollution (HAP).

METHODS AND DATA SOURCES

Searches of peer-review and grey literature in both English and Bahasa Indonesian were conducted and supplemented by interviews with key informants, data from the National Statistics Agency and results from household surveys. The data were extracted and analyzed using an Implementation Science approach.

RESULTS

The main kerosene to LPG conversion phase took place in highly populated kerosene dependent areas between 2007-2012 reaching over 50 million households, approximately two thirds of all households in Indonesia. Since then the drive to expand LPG use has continued at a slower pace, especially in more remote provinces where solid fuel is more widely used. Over 57 million LPG start up kits were distributed as of 2015. Beginning in 2018, the open subsidy for LPG is expected to be replaced by one targeted at lower income households. While the main conversion phase has been highlighted as an example of effective and impressively fast fuel switching at scale, the impact on domestic biomass use remains limited.

CONCLUSIONS

Addressing HAP and the health impacts associated with kerosene and biomass use was never an objective of the program. Consequently, there is limited evidence of impact in this area, and in hindsight, missed opportunities in terms of influencing cooking behavior change among biomass users, who are more at risk.

Building a consumer market for ethanol-methanol cooking fuel in Lagos, Nigeria

A recently completed randomized controlled study in Nigeria that transitioned pregnant women from traditional fuels to ethanol in their cook stoves demonstrated improved pregnancy outcomes in mothers and children. We subsequently conducted a pilot study of 30 households in Lagos, Nigeria, to determine the acceptability of blended ethanol/methanol as cooking fuel and willingness to pay for the Clean Cook stove. A third of the pilot participants expressed a willingness to purchase the stove for the minimum price of 42 USD or more. Fuel sales data suggest sustained, but non-exclusive, use of the CleanCook stove. These results will influence the final design and implementation of a planned 2500 stove commercial pilot that is scheduled to start in Nigeria in August 2018.

The Government-led initiative for LPG scale-up in Cameroon: programme development and initial evaluation

In 2016, the government of Cameroon, a central African country heavily reliant on wood fuel for cooking, published a Masterplan for increasing primary use of LPG from 20% to 58% of households by 2035. Developed via a multi-sectoral committee with support from the Global LPG Partnership, the plan envisages a 400 million Euro investment program to 2030, focused on increasing LPG cylinder numbers, key infrastructure, and enhanced regulation. This case study describes the Masterplan process and investment proposals and draws on community studies and stakeholder interviews to identify factors likely to impact on the planned expansion of LPG use.

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 PM_2.5 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 PM_2.5 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 PM_2.5 and the 24 h AQG for CO, respectively, with on average 97% of homes meeting the guideline for PM_2.5. Similarly, all four plancha-type stoves were ISO IWA Tier 4 for indoor emissions of CO and Tier 3 for indoor emissions of PM_2.5. 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 PM_2.5 and the 24 h AQG for CO for the scenario modeled in this study.

Light absorption of organic carbon emitted from burning wood, charcoal, and kerosene in household cookstoves

Household cookstove emissions are an important source of carbonaceous aerosols globally. The light-absorbing organic carbon (OC), also termed brown carbon (BrC), from cookstove emissions can impact the Earth's radiative balance, but is rarely investigated. In this work, PM_2.5 filter samples were collected during combustion experiments with red oak wood, charcoal, and kerosene in a variety of cookstoves mainly at two water boiling test phases (cold start CS, hot start HS). Samples were extracted in methanol and extracts were examined using spectrophotometry. The mass absorption coefficients (MAC_λ, m² g^-1) at five wavelengths (365, 400, 450, 500, and 550 nm) were mostly inter-correlated and were used as a measurement proxy for BrC. The MAC₃₆₅ for red oak combustion during the CS phase correlated strongly to the elemental carbon (EC)/OC mass ratio, indicating a dependency of BrC absorption on burn conditions. The emissions from cookstoves burning red oak have an average MAC_λ 2-6 times greater than those burning charcoal and kerosene, and around 3-4 times greater than that from biomass burning measured in previous studies. These results suggest that residential cookstove emissions could contribute largely to ambient BrC, and the simulation of BrC radiative forcing in climate models for biofuel combustion in cookstoves should be treated specifically and separated from open biomass burning.