Solid fuel use and cardiovascular events: A systematic review and meta-analysis of observational studies

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

BACKGROUND

As 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.

METHODS

A 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.

RESULTS

A 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.

CONCLUSION

A 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.

Effects of air pollutants exposure on frailty risk: A systematic review and meta-analysis

Air pollutants have been investigated to be associated with many health issues. Recently, increasing epidemiological studies have suggested the association between air pollution exposure and risk of frailty with inconsistent findings. This systematic review and meta-analysis was to summarize and evaluate effects of exposure to various air pollutants on risk of frailty. PubMed, Embase, Scopus and Web of Science were systematically searched for relevant studies published before May 11, 2024. Studies that explored the potential relationship between exposure to air pollutants (PM2.5, PM10, O3, NOx, solid fuel, secondhand tobacco, and air quality) and risk of frailty were included. The quality of cross-sectional and cohort studies was evaluated using an eight-item assessment instrument for epidemiological studies and Newcastle-Ottawa Scale, respectively. A total of 9,929 papers were retrieved, of which 20 met the inclusion criteria. Meta-analysis indicated that PM2.5 exposure was significantly associated with frailty assessed by the frailty index [OR (95% CI): 1.24 (1,11-1.38) per 10 μg/m3 increment]. Moreover, solid fuel exposures were significantly associated with an increased risk of frailty assessed by the frailty phenotype [OR (95% CI): 1.91 (1.09-3.34)] or the frailty index [OR (95% CI): 1.25 (1.11-1.41)]. Exposure to PM2.5 and solid fuel increases the risk of frailty. Environmental protection policies and public health measures should be developed to reduce PM2.5 concentrations. Effective measures, such as improving stoves and using clean fuels, should be taken to reduce indoor air pollution levels.

Risk assessment of unclean cooking energy usage from the perspective of subjective wellbeing: The mediating role of perceived physical and mental health

Although outdoor air pollution has been associated with adverse health outcomes and decreased subjective welfare, there has been a lack of research investigating the potential risks associated with indoor unclean cooking energy usage from the perspective of subjective wellbeing. This paper systematically assesses the risks of unclean cooking fuel usage from the novel perspective of subjective welfare and examines the mediating role of perceived physical and mental health applying a large-scale nationally representative dataset. Analytical results demonstrate that the usage of unclean cooking energy has significantly negative impacts on subjective wellbeing, and this finding has been confirmed through various robustness tests. The mechanism behind this impact is that unclean cooking fuel usage reduces people's perceived physical and mental health status, which in turn decreases their subjective wellness. Furthermore, the negative consequences of using unclean cooking energy on subjective wellbeing are particularly pronounced among certain demographic groups, including older, lower educated, married individuals as well as those with lower economic status, uncovered by medical insurance and having less social capital. Findings of this study highlight the risks linked to unclean cooking energy usage, as evidenced in the negative impact on perceived health and subjective wellbeing. In light of the increasing focus on improving indoor environment as well as enhancing people's health and wellbeing, results of this paper emphasize the significance of promoting access to cleaner and healthier energy.

Dose-response meta-analysis of ultra-processed food with the risk of cardiovascular events and all-cause mortality: evidence from prospective cohort studies

Background: Previous meta-analyses included abundant cross-sectional studies, and/or only assessed high versus low categories of UPF consumption. We conducted this meta-analysis based on prospective cohort studies to estimate the dose-response associations of UPF consumption with the risk of cardiovascular events (CVEs) and all-cause mortality among general adults. Methods: PubMed, Embase, and Web of Science were searched for relevant articles published up to August 17, 2021, and newly published articles between August 17, 2021 and July 21, 2022 were re-searched. Random-effects models were used to estimate the summary relative risks (RRs) and confidence intervals (CIs). Generalized least squares regression was used to estimate the linear dose-response associations of each additional serving of UPF. Restricted cubic splines were used to model the possible nonlinear trends. Results: Eleven eligible papers (17 analyses) were finally identified. The pooled effect size for the highest versus lowest category of UPF consumption showed positive associations with the risk of CVEs (RR = 1.35, 95% CI, 1.18-1.54) and all-cause mortality (RR = 1.21, 95% CI, 1.15-1.27). For each additional daily serving of UPF, the risk increased by 4% (RR = 1.04, 95% CI, 1.02-1.06) for CVEs and 2% (RR = 1.02, 95% CI, 1.01-1.03) for all-cause mortality. With increasing UPF intake, the risk of CVEs reflected a linear upward trend (P_nonlinearity = 0.095), while all-cause mortality reflected a nonlinear upward trend (P_nonlinearity = 0.039). Conclusion: Our findings based on prospective cohorts suggested that any increased level of UPF consumption was linked to higher CVEs and mortality risk. Thus, the recommendation is to control the intake of UPF in daily diet.

Associations between Household Solid Fuel Use, Obesity, and Cardiometabolic Health in China: A Cohort Study from 2011 to 2018

This study aims to explore the longitudinal relationship between solid fuel use and CMD incidence based on a nationally representative follow-up cohort study. A total of 6038 participants of the China Health and Retirement Longitudinal Study (CHARLS) were enrolled in the study. CMD is a cluster of diseases that include heart disease, stroke, and type 2 diabetes. Cox proportional-hazards regression models were used to examine the association between solid fuel use and the incidence or multimorbidity of CMD. The interactions between overweight or obesity and household air pollution on CMD incidence were also investigated. In the present study, solid fuel use from cooking or heating, separately or simultaneously, was positively associated with CMD incidence. Elevated solid fuel use was significantly associated with a higher risk of CMD incidence (HR = 1.25, 95% CI: 1.09, 1.43 for cooking; HR = 1.27, 95% CI: 1.11, 1.45 for heating). A statistically significant interaction between household solid fuel and OW/OB on the incidence of CMD and Cardiometabolic multimorbidity was also observed (p < 0.05). Our findings show that household solid fuel is a risk factor for the incidence of CMD. Therefore, reducing household solid fuel use and promoting clean energy may have great public health value for the prevention of CMD.

Associations of Household Solid Fuel Use With Falls and Fall-Related Injuries in Middle-Aged and Older Population in China: A Cohort Study

Objective: This study evaluated the associations of solid fuels with incidence of falls and fall-related injuries. Methods: Data were taken from wave 1∼4 of the China Health and Retirement Longitudinal Study, including 15,651 participants aged 45 years and older. Modified Poisson regression was used to examine the associations of solid fuels with falls and fall-related injuries. Results: Modified Poisson regression analysis showed that solid fuels users for cooking had an increasing incidence of falls and fall-related injuries, with RR of 1.211 (95% CI: 1.124, 1.305) and 1.248 (95% CI: 1.107, 1.408); for heating had an incidence, with RR of 1.178 (95% CI: 1.062, 1.306) and 1.134 (95% CI: 0.963, 1.335); combined for cooking and heating, with RR of 1.247 (95% CI: 1.105, 1.408) and 1.185 (95% CI: 0.982, 1.431). Conclusion: Our study suggests that solid fuel use is associated with a higher incidence of falls and fall-related injuries among adults aged 45 years and older in China. It is necessary to restrict solid fuel use to reduce household air pollution and make stronger environmental protection policies to improve household environment.

Associations of cooking fuel types and daily cooking duration with sleep quality in rural adults: Effect modification of kitchen ventilation

BACKGROUND

Associations of combined different cooking fuel types and cooking duration with sleep quality were scarcely reported. This study aimed to explore the associations of exposure to household air pollution (HAP) from different cooking fuel types and cooking duration with sleep quality and examine the effect modification of kitchen ventilation on these associations.

METHODS

A total of 28,135 eligible participants were obtained from the Henan rural cohort study. Sleep quality was assessed by the Pittsburgh sleep quality index (PSQI), and participants with a PSQI score > 5 were identified as having poor sleep quality. A questionnaire was used to collect the cooking fuel types, cooking frequency, cooking duration, and kitchen ventilation. The average daily cooking duration was calculated as the cooking frequency per week multiplied by the cooking duration for each meal divided by 7.

RESULTS

Both domestic fuel use and cooking duration were positively related to poor sleep quality. The solid fuel users with a cooking duration ≥1.5 h/day had a higher prevalence of poor sleep quality (OR: 1.390, 95% CI: 1.233, 1.567), relative to those who never cooked. Notably, the estimated OR and 95% CI for poor sleep quality of clean fuel users with a cooking duration <1.5 h/day plus mechanical or natural ventilation versus those who never cooked was 1.05 (0.933, 1.187) or 1.306 (1.163, 1.466) and these associations were modified by kitchen ventilation.

CONCLUSION

Positive associations of combined different cooking fuel types and cooking duration with the prevalence of poor sleep quality were attenuated by kitchen ventilation, implying that installing mechanical ventilation may be an effective measure to improve sleep quality in low- and middle-income countries. These results need to be confirmed by future studies, which measure HAP more accurately using personal monitoring devices or behavior diaries.

Indoor Solid Fuel Use and Non-Neoplastic Digestive System Diseases: A Population-Based Cohort Study Among Chinese Middle-Aged and Older Population

Objectives: We tended to explore the association of indoor air pollution (IAP) and non-neoplastic digestive system diseases (NNDSD) among the Chinese middle-aged and older population. Methods: From 2011 to 2018, we included 7884 NNDSD-free adults from the China Health and Retirement Longitudinal Study (CHARLS). Physician-diagnosed NNDSD was obtained by self-reported information at baseline and updated across follow-up surveys. We investigated the associations between baseline exposure of solid fuel use for cooking and/or heating and NNDSD diagnosed during follow-up through Cox proportional hazard models. Furthermore, we examined the relationship between cooking fuel switching and NNDSD diagnosed during follow-up. Results: Solid fuel use for cooking and/or heating was positively associated with NNDSD after adjusting for potential confounders. The risk of NNDSD among subjects who always use solid fuel for cooking (adjusted hazard ratio [aHR]: 1.42; 95% confidence interval [CI]: 1.09, 1.84) was higher than those with always clean fuels. Moreover, we found a lower NNDSD risk among participants who switched from solid to clean cooking fuel (aHR: 0.65; 95% CI: 0.49, 0.87) than those with always solid fuels. Conclusion: Our present study shows that indoor solid fuel use is a dependent risk factor for NNDSD. Moreover, switching to clean fuel may contribute to the prevention of digestive system illnesses.

Associations between household solid fuel use and activities of daily living trajectories: A nationwide longitudinal study of middle and older adults in China

BACKGROUND

More studies focus on reporting the effects of ambient air pollution on physical activity while ignoring the hazards of indoor air pollution caused by household solid fuel use. Moreover, the impact of individual cognitive and depressive status on the health effects of air pollution is often overlooked.

OBJECTIVE

We examined the association between household solid fuel and activities of daily living (ADL) trajectories, and further examined this association in homogeneous subgroups of cognitive or depressive trajectories.

METHODS

Participants were from the China Health and Retirement Longitudinal Study, which conducted four waves of surveys from 2011 to 2018. We collected information on participants' household fuel use, then the ADL, cognitive and depressive performances were assessed in each wave. The latent growth mixture model (LGMM) was used to identify the optimal trajectory class for ADL, cognition, and depression. Then, the multinomial logistic regression was used to assess the association between solid fuel use and ADL trajectories in total population, as well as subgroups with different cognitive or depression trajectories. Furthermore, we examined the association between switching household fuel types and ADL trajectories across the four-wave survey.

RESULTS

The study sample included 7052 participants. We identified three ADL trajectory classes in total population: "Low-stable", "Moderate-anterior rise", and "Moderate-posterior rise". The multinomial logistic regression results showed that solid fuel use was associated with elevated odds for the adverse ADL trajectories, and this association was still shown in homogeneous subgroups of cognitive or depressive trajectories, while some effects were less significant. In addition, the risk of adverse ADL trajectories generally increases with the times of solid fuel use across the four-wave survey.

CONCLUSIONS

For middle and older adults in China, household solid fuel use was not conducive to physical activity development, which inspires that a further transformation to cleaner fuels is an important intervention.

Lower socioeconomic status strengthens the effect of cooking fuel use on anemia risk and anemia-related parameters: Findings from the Henan Rural Cohort

The established evidence of cooking fuel use and socioeconomic status related to anemia is limited in low- and middle-income countries. The current study aims to examine the independent and combined effects of cooking fuel use and socioeconomic status on anemia risk as well as anemia-related parameters in rural China. A total of 21,050 participants were included from the baseline of the Henan Rural Cohort. Anemia was determined according to the World Health Organization criteria. Data on cooking fuel use (electricity, gas and solid fuel) and socioeconomic status (education and income levels) were collected using a standardized questionnaire by face-to-face interview. Logistic and linear regression models were applied to evaluate the effects of cooking fuel use or socioeconomic indicators on anemia risk, hemoglobin (HGB), red blood count (RBC), and hematocrit (HCT) levels. Using gas or solid fuel for cooking was positively associated with prevalent anemia risk and negatively related to HGB, RBC, and HCT levels compared to using electricity. Significant independent associations were also found between socioeconomic status (education and income levels) and prevalent anemia risk as well as these anemia-related parameters. In general, with decreased socioeconomic status, associations of using gas or solid fuel for cooking with advanced anemia risk as well as lower anemia-related parameters were increased. Furthermore, participants using gas or solid fuel for cooking and with lower education or income level were related to increased high anemia risk as well as low HGB, RBC and HCT levels, compared to those using electricity for cooking and with high education or income level (P <0.05 for all). The finding suggested that lower socioeconomic status strengthens the adverse effect of cooking fuel use on the higher anemia risk and lower HGB, RBC, and HCT levels in rural China.

Indoor air pollution from solid fuel on children pneumonia in low- and middle-income countries: a systematic review and meta-analysis

An updated systematic review was conducted to assessing on the association between indoor air pollution caused by household energy consumption and childhood pneumonia in low- and middle-income countries. We performed a meta-analysis from the electronic databases of PubMed, Cochrane library, Web of Science, EMBASE. Studies were selected when they reported childhood pneumonia or ALRI in relation to indoor air pollution resulted from solid fuel. Studies must provide results on exposure prevalence of children aged below 5 years from Asia or Africa. We devoted ourselves to identifying randomized controlled experiments and observational epidemiological researches, which revealed the relation between household usage of solid fuel and childhood pneumonia. Among 1954 articles, 276 were reviewed thoroughly and 16 conduced to such a meta-analysis. It was found that there is a significant relationship between the solid fuel combustion and increasing risk of childhood pneumonia (OR = 1.66, 95%CI 1.36-2.02). The summary odds ratios from biomass use and mixed fuel use were, respectively, 1.86 (95%CI 1.15-3.02) and 1.58 (95%CI 1.38-1.81), with substantial between study heterogeneity (I² = 87.2% and 29.2%, respectively). According to the subgroup analysis along with the meta-regression analysis, the risk of using solid fuel in Asian regions is higher than that in African regions. Studies based on non-hospital participates (I² = 49.5%) may also a source of heterogeneity. We found that indoor air pollution generated by the usage of solid fuel might be a significant risk factor for pneumonia in children and suggested improving the indoor air quality by promoting cleaner fuel will be important in undeveloped countries.