Solid Fuels For Cooking Research Articles

Mitigating Household Air Pollution Exposure Through Kitchen Renovation

Globally, over three billion people rely on traditional solid fuels for cooking and heating, leading to significant household air pollution and critical public health concerns. While transitioning to clean energy carriers faces challenges of accessibility and affordability—especially among low-income, rural populations—alternative strategies like kitchen layout modifications and the use of ventilation fans may effectively reduce exposure to pollutants. Here, we analyze factors influencing the adoption of separated kitchens and mechanical ventilation and evaluate changes in human exposure to PM2.5 under different kitchen renovation scenarios by conducting a nationwide survey of household kitchen characteristics in rural China. We found that although 82% of rural households have kitchens separated from other rooms, only 34% use mechanical ventilation. The adoption of ventilation fans is significantly influenced by income and education levels. We estimate that widespread implementation of ventilation fans and separated kitchen designs could prevent approximately 67400 premature deaths annually, resulting in a health benefit of about USD 19 billion per year—substantially exceeding the costs involved. These findings suggest that cost-effective kitchen renovations offer enormous potential for substantial health benefits and present a practical solution compared to the challenges of clean energy transitions in rural areas.

Association between exposure to smoke from cooking fuels and anaemia among women of reproductive age in Ghana

In low- and middle-income countries, indoor air pollution (IAP) is a serious public health concern, especially for women and children who cook with solid fuels. IAP exposure has been linked to a number of medical conditions, including pneumonia, ischemic heart disease, stroke, chronic obstructive pulmonary disease (COPD), lung cancer, and anaemia. Around 500 million women of reproductive age (WRA) suffer from anaemia globally, with an estimated 190 million cases in sub-Saharan Africa (SSA). This study, which is based on prior research, investigates the relationship between IAP exposure and anaemia among WRA in Ghana. A diverse sample of 2,406 WRA living in Ghana were interviewed, of which 58.06% were anaemic and used high-pollutant fuels for cooking. Age, place of residence, region, education level, religion, ethnicity, wealth index, type of drinking water, type of toilet facility, and type of cooking fuels were all found to be significantly linked with anaemic state by bivariate analysis. Type of cooking fuels utilized, age, region of residence, and the type of residence were shown to be significant predictors of anaemia status using sequential binary logit regression models. The results emphasise the critical need for efforts to promote the usage of clean cooking fuel in an attempt to lower anaemia prevalence in Ghana. To reduce dependency on solid fuels for cooking, initiatives should promote the use of cleaner cooking fuels and enhance the socioeconomic status of households. These interventions could have significant public health effects by reducing the burden of anaemia and improving maternal and child health outcomes due to the prevalence of anaemia among WRA. Overall, this study sheds light on the relationship between IAP exposure and anaemia in Ghana and highlights the demand for focused public health initiatives to address this serious health problem.

Association of solid fuel use with cognitive function and the modifying role of lifestyle: A nationwide cohort study in China

BackgroundAs opposed to a healthy lifestyle, indoor air pollution from solid fuel use may be harmful for cognitive function. However, the extent to which lifestyle modifies the association between solid fuel use and cognitive function remains unknown. MethodsA total of 21,008 individuals aged 16 to 92 were enrolled in 2010 and followed up to 2014 in the China Family Panel Studies (CFPS). Cognitive function was assessed using standardized math and word tests in two waves. Solid fuel use at baseline was assessed by self-reporting of firewood, straw, or coal used for cooking. Lifestyle profile was classified into two groups (favorable vs. unfavorable) based on five modifiable lifestyle factors including alcohol drinking, smoking, body mass index, diet, and physical activity. Linear mixed-effects models were employed to assess the association of solid fuel use and lifestyle with cognitive function. The effect modification of lifestyle was analyzed. ResultsA total of 49.7% of the study population used solid fuels for cooking and 17.4% had a favorable lifestyle. Solid fuel use was associated with a significant decrease in cognitive function (β = −0.29, 95% CI: −0.39, −0.19 for math test; β = −0.62, 95% CI: −0.84, −0.41 for word test). Lifestyle significantly modified this association (p-interaction: 0.006 for math test; 0.016 for word test), with the corresponding association being less pronounced among participants adhering to a favorable lifestyle compared to those with an unfavorable lifestyle. ConclusionA favorable lifestyle may attenuate the adverse association between solid fuel use and cognitive function. Adopting a favorable lifestyle has the potential to mitigate the adverse neurological effects due to indoor air pollution.

Indoor air pollution by solid fuel usages for cooking is longitudinally associated with possible sarcopenia in middle-aged Chinese population.

The Asia Working Group of Sarcopenia (AWGS) 2019 consensus proposed a new concept named "possible sarcopenia". The present study was to estimate the association between indoor air pollution by solid fuel usages for cooking and possible sarcopenia among middle-aged and older Chinese population. A longitudinal cohort analysis was carried out using nationally representative data from the China Health and Retirement Longitudinal Study (CHARLS). A total of 17,708 participants were recruited and followed up in the CHARLS. Cox proportional hazards models were used to estimate the effects of cooking fuel usages on the new onset of possible sarcopenia. Stratified analyses were performed according to gender and age, and sensitivity analyses were performed using the complete dataset. A total of 4,653 participants were included in the final cohort analysis. During the follow-up of 4 years (2011-2015), a total of 1,532 (32.92%) participants developed new-onset possible sarcopenia. Compared with clean fuel usages for cooking, solid fuel usages were associated with a higher risk of possible sarcopenia (HR = 1.37, 95% CI = 1.23-1.52, p-value < 0.001). After adjusting for potential confounders, there was a trend for association between solid fuel usages and an increased risk of possible sarcopenia. Stratified analyses by gender and age demonstrated a stronger association of the solid fuel usages with possible sarcopenia in the middle-aged female participants (Model 1: HR = 1.83, 95% CI = 1.24-2.69, p-value = 0.002; Model 2: HR = 1.65, 95% CI = 1.10-2.47, p-value = 0.016). Sensitivity analyses indicated that the results were robust. Indoor air pollution from solid fuel usages for cooking was a modifiable risk factor for sarcopenia, especially in middle-aged female population. These findings provide a new prevention strategy to reduce the growing burden of sarcopenia, especially for middle-aged female individuals using solid fuels for cooking.

Pain in Solid and Clean Fuel Using Households

Household air pollution from solid cooking fuel use influences multiple health outcomes, but its association with body pain remains poorly understood. This was a longitudinal study of 8880 adults who participated in the China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2018. Household cooking fuels were extracted from the baseline household questionnaire. Transitions in cooking fuels from 2011 to 2018 were also identified. Body pain status was reported in the three waves of surveys conducted in 2011, 2015, and 2018. The associations between cooking fuel type, fuel transition, and pain site number were examined using generalized estimating equations. Among the 8880 participants, 41.4% (n=3680) primarily used clean fuels for cooking, and 58.6% (n=5200) used solid ones at baseline. Cooking with solid fuels was associated with more pain sites (incidence rate ratio (IRR): 1.14; 95% confidence interval (CI): 1.08 to 1.21), but a slower rate of pain sites increases from 2011 to 2018 (IRR=0.78; 95% CI: 0.71 to 0.86, for 2018×solid fuels). Compared with those who persistently used clean fuels for cooking, the number of pain sites increased by 10% in participants who transiting from using solid to clean fuels (IRR=1.10; 95% CI: 1.04 to 1.18), by 21% in those transiting from cooking with clean to solid fuels (IRR=1.21: 95% CI: 1.08 to 1.35) and by 25% among those persistent using solid fuels for cooking (IRR=1.25; 95% CI: 1.18 to 1.34). Our findings provided new evidence linking using solid fuels for cooking with more pain sites, but a slower rate of pain sites increases. Public health efforts should focus on fuel transition and take measures to help clean fuels spread.

Association between cooking fuel exposure and respiratory health: Longitudinal evidence from the China Health and Retirement Longitudinal Study (CHARLS)

The epidemiological evidences for the association between cooking fuel exposure and respiratory health were inconsistent, and repeated-measures prospective evaluation of cooking fuel exposure was still lacking. We assessed the longitudinal association of chronic lung disease (CLD) and lung function with cooking fuel types among Chinese adults aged ≥ 40 years. In this prospective, nationwide representative cohort of the China Health and Retirement Longitudinal Study from 2011 to 2018, 9004 participants from 28 provinces in China were included. CLD was identified based on self-reported physician diagnosis in 2018. Lung function was assessed by peak expiratory flow (PEF) in 2011, 2013 and 2015. Multivariable logistic and linear mixed-effects repeated-measures models were conducted to measure the associations of CLD and PEF with cooking fuel types. Three-level mixed-effects model was performed as sensitivity analysis. Among the participants, 3508 and 3548 participants used persistent solid and clean cooking fuels throughout the survey, and 1948 participants who used solid cooking fuels at baseline switched to clean cooking fuels. Use of persistent clean cooking fuels (adjusted odds ratio [aOR] = 0.73, 95 % confidence interval [CI]: 0.61, 0.88) and switch of solid fuels to clean fuels (aOR = 0.81, 95 % CI: 0.67, 0.98) were associated with lower risk of CLD. The use of clean cooking fuels throughout the survey and switch of solid fuels to clean fuels in 2013 were also significantly associated with higher PEF level. Similar results were observed in stratified analyses and different statistical models. The evidence from CHARLS cohort suggested that reducing solid cooking fuel exposure was associated with lower risk of CLD and better lung function. Given the recent evidence, improving household air quality will reduce the burden of chronic lung diseases.

Household fuel and direct carbon emission disparity in rural China

Universal access to clean fuels in household use is one explicit indicator of sustainable development while currently still billions of people rely on solid fuels for daily cooking. Despite of the recognized clean transition trend in general, disparities in household energy mix in different activities (e.g. cooking and heating) and historical trends remain to be elucidated. In this study, we revealed the historical changing trend of the disparity in household cooking and heating activities and associated carbon emissions in rural China. The study found that the poor had higher total direct energy consumption but used less modern energy, especially in cooking activities, in which the poor consumed 60 % more energy than the rich. The disparity in modern household energy use decreased over time, but conversely the disparity in total residential energy consumption increased due to the different energy elasticities as income increases. Though per-capita household CO2 and Black Carbon (BC) emissions were decreasing under switching to modern energies, the disparity in household CO2 and BC deepened over time, and the low-income groups emitted ∼ 10 kg CO2 more compared to the high-income population. Relying solely on spontaneous clean cooking transition had limited impacts in reducing disparities in household energy and carbon emissions, whereas improving access to modern energy had substantial potential to reduce energy consumption and carbon emissions and its disparity. Differentiated energy-related policies to promote high-efficiency modern heating energies affordable for the low-income population should be developed to reduce the disparity, and consequently benefit human health and climate change equally.

Impact of indoor air pollution from cooking fuel usage and practices on self-reported health among older adults in India: Evidence from LASI

This research aims to explore the impact of various components of Indoor air pollution (IAP) on the Self-Reported Health (SRH) of older adults in India. Using a sample of 27,090 from the Longitudinal Aging Study in India (LASI) Wave-1, a multiple binary logistic regression model was employed to identify specific risk factors associated with poor SRH among older adults. Adjusting for demographic, socioeconomic, and IAP-related components, it was revealed that IAP significantly contributes to poor SRH. The adjusted model indicated that individuals using solid cooking fuels face a higher risk of poor SRH compared to those using liquid fuels. Additionally, individuals not using electric chimneys and cooking near windows are associated with an elevated risk of poor SRH, highlighting the importance of adequate ventilation. Health risk factors, including lung disease, diabetes, cough, and depression, further contribute to poor SRH among older adults exposed to IAP. Overall, the study offers crucial insights for policymakers, healthcare professionals, and environmentalists to improve the well-being of the vulnerable older population in India.

Sustainable biogas production potential in Nepal using waste biomass: A spatial analysis

AbstractBiogas plays a significant part in replacing solid biomass and fossil fuels for cooking. However, the implementation of appropriate policies to promote the development of biogas plants is hindered by a lack of adequate assessment of the biogas potential in Nepal. Thus, we estimate the potential of biogas production at the district level of Nepal from available waste biomass, including livestock manure, agricultural residues, and organic fraction of municipal solid waste (OFMSW). Our estimates show the theoretical potential of biogas production from livestock manure of 1890 million m3 year−1, agricultural residues of 2290 million m3 year−1, and OFMSW of 234 million m3 year−1. The total biogas production is 4412 million m3 year−1, equivalent to 153 million liquefied petroleum gas (LPG) cylinders yearly. Using this biogas potential to replace LPG and solid biomass for cooking could result in avoided CO2, CO, and PM2.5 emissions of 6.3 million tons year−1, 0.4 million tons year−1, and 0.04 million tons year−1, respectively. Our findings suggest that the Terai districts of Morang, Sunsari, Saptari, and Banke, as well as the Hilly districts of Kavrepalanchok, Dhading, and Nuwakot, have a significant amount of biogas‐producing potential. Utilising this potential could also contribute to achieving several Sustainable Development Goals and a clean cooking energy transition in Nepal. For this, governments need careful planning, designing, policy support, and facilitation on bio‐resource management and utilisation at the local level.

Household use of solid fuel and sarcopenia among middle-aged and older adults: The China Health and Retirement Longitudinal Study

ObjectiveFew studies have examined the effects of air pollution on the risk of sarcopenia, especially pollution in indoor settings. We explored the cross-sectional and longitudinal associations of household use of solid fuel for cooking and heating, separately and simultaneously, with risk of sarcopenia. MethodsCross-sectional and follow-up data from the China Health and Retirement Longitudinal Study were used. Multivariable-adjusted generalized linear models and Cox proportional hazards regression models were performed to estimate the odds ratio and hazard ratio for sarcopenia, respectively. Results11,494 (median age: 57.0 years; 47.4 % males) and 7483 (median age: 57.0 years; 46.9 % males) participants were included in the cross-sectional and longitudinal study, respectively. After fully adjusting for covariates, including outdoor concentration of particulate matter (PM2.5), both the use of solid fuels for cooking and use for heating were positively associated with incident sarcopenia in the longitudinal analyses, with hazard ratios (95 % confidence interval) of 1.56 (1.28–1.89) and 1.26 (1.04–1.52), respectively. Moreover, significant multiplicative and/or additive interactions were observed between age, smoking and cooking with solid fuel and risk of sarcopenia (all P for interaction <0.05). Similar results were found in the cross-sectional analyses. ConclusionsHousehold use of solid fuel was significantly associated with a higher risk of sarcopenia, while ageing and smoking had synergetic effects with burning solid fuels on the risk of sarcopenia. Our results highlight the importance of taking multi-pronged measures with respect to both air pollution and healthy lifestyle to prevent sarcopenia and promote healthy ageing.

Exposure to indoor air pollution and angina among aging adults in India: evidence from a large-scale nationwide study

ABSTRACT This study tried to understand the association between exposure to indoor air pollution and angina among the aging population in India. We utilized the data from the Longitudinal Ageing Study in India (LASI) Wave–1 (2017–2018), with a sample of 62,846 aging adults. We applied Chi-square and multivariate logistic regression models. The odds of angina were higher among individuals living in households that used solid fuels for cooking (aOR = 1.15, 99% CI- 1.09-1.20), had someone smoked inside the house (aOR = 1.12, 99% CI- 1.07-1.18), and households that used of incenses inside the home (aOR = 1.11, 99% CI- 1.05-1.18). In addition, it was also found that work-limiting impairment, unhealthy behaviors, and poor health status increased the odds of angina. These results indicate the need to reduce in-house air pollution by promoting clean fuel usage and changing attitudes and practices. Other implications are discussed.

Indoor Air Pollution from Household Cooking and Associated Health Hazards of Selected Rural Communities of Madhupur Tract in Bangladesh

Indoor air pollution is deemed one of the most severe environmental pollutions that occur mainly due to the inefficient and incomplete combustion of solid cooking fuels, which emits different types of particulate matter (PM2.5, PM10). Therefore, this study was organized in the hilly rural area of Sagordighi of Tangail district in Bangladesh to monitor the atmospheric particulate matters PM2.5, PM10 and CO (carbon monoxide) concentrations from the rural kitchens as well as the possible health hazards due to exposure of the air pollutants. One hundred and thirty air samples were collected from the kitchens by using Airveda air quality monitor and Testo 317-3 - Ambient CO meter to monitor the particulate matter and carbon-monoxide concentrations respectively during cooking and non-cooking time. A survey was also conducted through questionnaire. The concentrations of PM2.5 fluctuated from 112-999 µgm-3 whereas the mean concentration was 401.88±232 µgm-3 during cooking time. On the other hand, PM10 concentration varied from 114-1999 µgm-3 were observed during cooking time with a mean concentration was 523.10±413 µgm-3. The concentration of PM2.5 varied from 32-362 µgm-3 at non-cooking period while the mean value was 81.38±41 µgm-3. The concentration of PM10 ranged between 55-429 µgm-3 at non-cooking period and the mean of PM10 was 109.51±51 µgm-3. The mean concentration of CO during cooking period was 51.52±17 ppm and it varied from 20 ppm to 96.4 ppm. On the contrary, the mean concentration of CO during non-cooking period was 6.60± 6 ppm and it fluctuated from 0 to 40 ppm. The concentration of atmospheric particulate matter showed the highest concentration during cooking time. Contemplation on the measured concentration of particulate matters, these values were greater than concentration found in many European cities and also surpassed the Bangladesh National Ambient Air Quality Standard. The monitored CO value exceeded the recommended value. Questionnaire survey result indicated that respondents suffered from various diseases due to household cooking activities such as facing eye irritation, headaches, dry cough, dizziness and nasal congestion during cooking time. This research suggests installation of improved cooking stoves and providing proper ventilation facilities in kitchen and using renewable energy as well as creating public awareness among rural communities for minimizing the impacts of pollutants emitted from cooking activities.

Biomass or LPG? A case study for unraveling cooking fuel choices and motivations of rural users in Maheshkhali Island, Bangladesh

Biomass fuel could effectively address the existing energy crisis in developing countries, including Bangladesh, yet its potential remains largely overlooked in scholarly and policy discussions. The objective of this study was to understand the people's perception of fuelwood, LPG, and cow dung as well as to identify factors influencing the choices of solid cooking fuels and the extent of daily fuelwood consumption in Maheshkhali, a secluded island off the coast of the Bay of Bengal in Bangladesh, characterized by its diverse landscapes. Primary data was collected through a questionnaire survey and focus group discussions and were analyzed using descriptive statistics, binomial logistic regression, and ordinary least squares regression (OLSR) to identify key determinants. Our findings suggest a pronounced preference for biomass fuel, as indicated by the odds ratio and user perceptions grounded in the central capability approach. The OLSR results indicate that cooking time, quantity collection, the number of school-going children, and educational score explain 82.5% of the total variance in fuelwood consumption, making them major driving factors. The household survey revealed a stark reliance on biomass fuel, with 87% of families using it exclusively, while only 4% rely solely on LPG. Fuelwood collection, primarily a task for women and children, also involved men who spent approximately five hours to traverse 1.5 km to collect 23 kg of biomass per trip. The strong biomass preference for fuel, in terms of central capability, underscores the challenges in motivating users to cleaner alternatives like LPG.

Characterization of risks and pathogenesis of respiratory diseases caused by rural atmospheric PM2.5

Forty-six percent of the world's population resides in rural areas, the majority of whom belong to vulnerable groups. They mainly use cheap solid fuels for cooking and heating, which release a large amount of PM2.5 and cause adverse effects to human health. PM2.5 exhibits urban-rural differences in its health risk to the respiratory system. However, the majority of research on this issue has focused on respiratory diseases induced by atmospheric PM2.5 in urban areas, while rural areas have been ignored for a long time, especially the pathogenesis of respiratory diseases. This is not helpful for promoting environmental equity to aid vulnerable groups under PM2.5 pollution. Thus, this study focuses on rural atmospheric PM2.5 in terms of its chemical components, toxicological effects, respiratory disease types, and pathogenesis, represented by PM2.5 from rural areas in the Sichuan Basin, China (Rural SC-PM2.5). In this study, organic carbon is the most significant component of Rural SC-PM2.5. Rural SC-PM2.5 significantly induces cytotoxicity, oxidative stress, and inflammatory response. Based on multiomics, bioinformatics, and molecular biology, Rural SC-PM2.5 inhibits ribonucleotide reductase regulatory subunit M2 (RRM2) to disrupt the cell cycle, impede DNA replication, and ultimately inhibit lung cell proliferation. Furthermore, this study supplements and supports the epidemic investigation. Through an analysis of the transcriptome and human disease database, it is found that Rural SC-PM2.5 may mainly involve pulmonary hypertension, sarcoidosis, and interstitial lung diseases; in particular, congenital diseases may be ignored by epidemiological surveys in rural areas, including tracheoesophageal fistula, submucous cleft of the hard palate, and congenital hypoplasia of the lung. This study contributes to a greater scientific understanding of the health risks posed by rural PM2.5, elucidates the pathogenesis of respiratory diseases, clarifies the types of respiratory diseases, and promotes environmental equity.

Household air pollution exposure and risk of tuberculosis: a case–control study of women in Lilongwe, Malawi

IntroductionGlobally, 3–4 billion people rely on solid fuels for cooking, and 1 billion use kerosene to light their homes. While household air pollution (HAP) emitted from burning these fuels has...

Association of Exposure to Indoor Air Pollution with Unhealthy Symptoms among Middle-aged and Older Adults in India: Evidence from a Large-scale Survey.

The usage of solid cooking fuels is widely prevalent in low and middle-income countries, including India, and contributes to indoor air pollution (IAP), which has detrimental health effects. Moreover, time spent inside the house increases as people age. In this context, the present study tried to understand the association between exposure to indoor air pollution and unhealthy symptoms, including shortness of breath, dizziness, headache, fatigue, wheezing, and cough among middle-aged and older adults in India. We extracted the unit-level individual data (N = 63 790) from the Longitudinal Aging Study in India (LASI)-Wave 1 (2017-2018). The statistical analyses used were Chi-square test and binary logistic regression, which estimated the odds ratio to identify the determinants of the unhealthy symptoms. The odds of shortness of breath (adjusted OR: 1.14, 99% CI: 1.05-1.23), dizziness (adjusted OR: 1.28, 99% CI: 1.21-1.35), fatigue (adjusted OR: 1.32, 99% CI: 1.26-1.39), wheezing (adjusted OR: 1.30, 99% CI: 1.19-1.42), and cough (adjusted OR: 1.36, 99% CI: 1.27-1.45) were higher among individuals from households where solid cooking fuels was used. Similarly, the odds of shortness of breath, headache, wheezing, and cough were higher among individuals with a household member who smoked inside the house. The results indicated that the odds of shortness of breath, headache, and cough were significantly lower among participants exposed to incense use. Based on the results of this study, we suggest developing programs to combat the sources of indoor air pollution and the associated unhealthy symptoms, especially in rural settings. It is also important to bring awareness and practice clean fuel usage at individual and community levels to improve population health.

Quantifying national household air pollution (HAP) exposure to PM2.5 in rural and urban areas

According to WHO (World Health Organization), in 2020, 14% of people in global urban areas relied on polluting solid fuels and technologies, compared with 52% of the rural population. The health impacts of such inequality are massive. It was estimated that 3.2 million premature deaths per year (2020), particularly in low-income and middle-income countries due to household air pollution (HAP). Several studies provide estimates of the exposure to fine particulate matter (PM2.5) from household air pollution (HAP-PM2.5) for users of different fuel/cookstove types in rural and urban areas. However, hardly any studies estimate the population-weighted exposure to HAP-PM2.5 at the global scale. A Bayesian hierarchical model was developed to estimate PM2.5 exposure coefficients and their uncertainties for an annual average of HAP-PM2.5 personal exposure. The predicted HAP-PM2.5 exposure at the user level was used to estimate the national-level exposure for the population living in urban and rural areas. The results suggest that switching from polluting solid fuels (biomass, charcoal, coal) to cleaner fuels (gas and electricity) for heating and cooking can potentially reduce the national-level HAP-PM2.5 personal exposure on average by 53%. However, there exists a significant disparity between rural and urban areas, partly reflecting inequality in energy access. More specifically, switching from polluting solid fuels for heating and cooking to cleaner fuels can reduce the personal exposure to HAP-PM2.5 in rural areas by 54% and in urban areas by 38%. The study indicates that increased access to clean fuels and improved stove interventions are needed to achieve the goals of universal energy access and equality between urban and rural areas.

Insight into personal exposure characteristics and health effects of PM2.5 and PM0.25-bound PAHs and their derivatives with different heating ways in the Fenwei Plain, China

Personal exposure (PE) to polycyclic aromatic hydrocarbons (PAHs) and their derivatives in particulate matter with two aerodynamic sizes of 2.5 and 0.25 μm (PM2.5 and PM0.25) from rural housewives was studied in the Fenwei Plain, China. A total of 15 households were divided into five different groups based on the type of solid fuel and heating device used, including biomass briquette-furnace (BBF), biomass-elevated Kang (BEK), outdoor lump coal-boiler (OLC), indoor briquette coal-stove (IBC), and electricity (ELE). The PE concentrations of the PAHs and biomarkers in urine collected from the participants were determined. The results showed that the PE concentrations of total quantified PAHs in the biomass group (i.e., BBF and BEK) were 2.2 and 2.0 times higher than those in the coal groups (i.e., OLC and IBC) in PM2.5 and PM0.25, respectively. The housewives who used biomass as fuel suffered from higher potential health impacts than the coal fuel users. The incremental lifetime cancer risk for the PAHs in PM2.5 in the BBF and BEK groups exceeded the international safety threshold. Furthermore, the PE concentrations of oxygenated PAH (o-PAHs) in PM2.5 and PM0.25 in the biomass groups and the nitrated PAHs (n-PAHs) in PM0.25 in the coal groups showed strong correlations with the biomarkers. The results of this study proved the associations between exposure to the different classes of PAHs and health hazards. The findings could also serve as a guideline in establishing efficient measures for using solid fuels for cooking and household warming in northern China.

Nepalese indoor cookstove smoke extracts alter human airway epithelial gene expression, DNA methylation and hydroxymethylation

Household air pollution caused by inefficient cooking practices causes 4 million deaths a year worldwide. In Nepal, 86% of the rural population use solid fuels for cooking. Over 25% of premature deaths associated with air pollution are respiratory in nature. Here we aimed to identify molecular signatures of different cookstove and fuel type exposures in human airway epithelial cells, to understand the mechanisms mediating cook stove smoke induced lung disease. Primary human airway epithelial cells in submerged culture were exposed to traditional cook stove (TCS), improved cook stove (ICS) and liquefied petroleum gas (LPG) stove smoke extracts. Changes to gene expression, DNA methylation and hydroxymethylation were measured by bulk RNA sequencing and HumanMethylationEPIC BeadChip following oxidative bisulphite conversion, respectively. TCS smoke extract alone reproducibly caused changes in the expression of 52 genes enriched for oxidative stress pathways. TCS, ICS and LPG smoke extract exposures were associated with distinct changes to DNA methylation and hydroxymethylation. A subset of TCS induced genes were associated with differentially methylated and/or hydroxymethylated CpGs sites, and enriched for the ferroptosis pathway and the upstream regulator NFE2L2. DNA methylation and hydroxymethylation changes not associated with a concurrent change in gene expression, were linked to biological processes and molecular pathways important to airway health, including neutrophil function, transforming growth factor beta signalling, GTPase activity, and cell junction organisation. Our data identified differential impacts of TCS, ICS and LPG cook stove smoke on the human airway epithelium transcriptome, DNA methylome and hydroxymethylome and provide further insight into the association between indoor air pollution exposure and chronic lung disease mechanisms.

Urban–rural disparity in global estimation of PM2·5 household air pollution and its attributable health burden

Polluting fuels and inefficient stove technologies are still a leading cause of premature deaths worldwide, particularly in low-income and middle-income countries. Previous studies of global household air pollution (HAP) have neither considered the estimation of PM2·5 at national level nor the corresponding attributable mortality burden. Additionally, the effects of climate and ambient air pollution on the global estimation of HAP-PM2·5 exposure for different urban and rural settings remain largely unknown. In this study, we include climatic effects to estimate the HAP-PM2·5 exposure from different fuel types and stove technologies in rural and urban settings separately and the related attributable global mortality burden. Bayesian hierarchical models were developed to estimate an annual average HAP-PM2·5 personal exposure and HAP-PM2·5 indoor concentration (including both outdoor and indoor sources). Model variables were selected from sample data in 282 peer-reviewed studies drawn and updated from the WHO Global HAP dataset. The PM2·5 exposure coefficients from the developed model were applied to the external datasets to predict the HAP-PM2·5 exposure globally (personal exposure in 62 countries and indoor concentration in 69 countries). Attributable mortality rate was estimated using a comparative risk assessment approach. Using weighted averages, the national level 24 h average HAP-PM2·5 exposure due to polluting and clean fuels and related death rate per 100 000 population were estimated. In 2020, household use of polluting solid fuels for cooking and heating led to a national-level average personal exposure of 151 μg/m3 (95% CI 133-169), with rural households having an average of 171 μg/m3 (153-189) and urban households an average of 92 μg/m3 (77-106). Use of clean fuels gave rise to a national-level average personal exposure of 69 μg/m3 (62-76), with a rural average of 76 μg/m3 (69-83) and an urban average of 49 μg/m3 (46-53). Personal exposure-attributable premature mortality (per 100 000 population) from the use of polluting solid fuels at national level was on average 78 (95% CI 69-87), with a rural average of 82 (73-90) and an urban average of 66 (57-75). The average attributable premature mortality (per 100 000 population) from the use of clean fuels at the national level is 62 (54-70), with a rural average of 66 (58-74) and an urban average of 52 (47-57). The estimated HAP-PM2·5 indoor concentration shows that the use of polluting solid fuels resulted in a national-level average of 412 μg/m3 (95% CI 353-471), with a rural average of 514 μg/m3 (446-582) and an urban average of 149 μg/m3 (126-173). The use of clean fuels (gas and electricity) led to an average PM2·5 indoor concentration of 135 μg/m3 (117-153), with a rural average of 174 μg/m3 (154-195) and an urban average of 71 μg/m3 (63-80). Using time-weighted HAP-PM2·5 indoor concentrations, the attributable premature death rate (per 100 000 population) from the use of polluting solid fuels at the national level is on average 78 (95% CI 72-84), the rural average being 84 (78-91) and the urban average 60 (54-66). From the use of clean fuels, the average attributable premature death rate (per 100 000 population) at the national level is 59 (53-64), the rural average being 68 (62-74) and the urban average 45 (41-50). A shift from polluting to clean fuels can reduce the average PM2·5 personal exposure by 53% and thereby lower the death rate. For all fuel types, the estimated average HAP-PM2·5 personal exposure and indoor concentrations exceed the WHO's Interim Target-1 average annual threshold. Policy interventions are urgently needed to greatly increase the use of clean fuels and stove technologies by 2030 to achieve the goal of affordable clean energy access, as set by the UN in 2015, and address health inequities in urban-rural settings. Wellcome Trust, The Lancet Countdown, the Engineering and Physical Sciences Research Council, and the Natural Environment Research Council.