In a recently published systematic review and meta-analysis Lancet Respiratory MedicineResearchers examined evidence across countries on the health effects of using gaseous fuels for heating and cooking. They found that transitioning from polluting fuels to household gaseous fuels may reduce health risks, particularly in low-income countries.
Household air pollution from solid fuel combustion causes 3.2 million avoidable deaths every year. The transition to cleaner liquid and gaseous fuels is critical for low- and middle-income countries (LMICs) and is thought to address this burden. This study synthesizes the evidence on the health impacts of domestic use of liquid and gaseous fuels, highlighting the urgent need for a clean transition to achieve the Sustainable Development Goals. Although electricity is the cleanest, low- and middle-income countries have limited access to electricity and therefore need scalable alternatives.
This systematic review and meta-analysis explores the health effects of gaseous and liquid fuels, excluding polluting liquid fuels used for lighting (solid fuels, kerosene), and highlights the potential respiratory effects of gas use, setting the stage for a rapid transition Global policy towards cleaner homes provides information dynamism.
About the study
The systematic review searched major databases such as PubMed, Scopus, MEDLINE, Cochrane Library, Environment Complete, Web of Science, GreenFile, Wanfang Data, Google Scholar, and CNKI. Studies published between 1980 and 2021 were selected, focusing on the health effects of cooking and heating with liquid and gaseous fuels (natural gas, liquefied petroleum gas (LPG), biogas). Studies related to lighting or specific pollutants and without health outcomes were excluded. A total of 216 studies were included in the systematic review and 116 studies were included in the meta-analysis.
Data were extracted using a 15-round refined Excel spreadsheet capturing study details, fuel types, comparators, population characteristics, health outcomes, and outcomes. The Liverpool Quality Assessment Tool (LQAT) assesses study quality, taking into account aspects such as selection, response bias, exposure measurement and confounding. Quality score (expressed as a percentage) is divided into at least moderate quality (>60%) and poor quality (≤60%). This approach aims to assess the potential impact of methodological quality on pooled effect estimates in meta-analyses, without assuming hierarchy of evidence.
The meta-analysis focused on five health effects: asthma (children and adults), acute lower respiratory tract infections, chronic lung disease, respiratory symptoms, and adverse pregnancy outcomes. Studies with consistent definitions of health status and exposure to any household energy gas fuel were brought together for analysis. Random-effects meta-analysis was used, with preferably adjusted estimates. Funnel plots and statistical tests assessed publication bias. Woodlands are stratified by age group and condition. Separate analyzes compared gaseous or liquid fuels to clean (electricity) and dirty (wood, charcoal, kerosene) reference groups, with sensitivity analyzes performed for studies with unclear reference groups.
Results and discussion
Studies show that gaseous fuels reduce the risk of asthma in adults by 35% compared to polluting fuels. However, no significant differences were observed in childhood asthma risk. For acute lower respiratory tract infection or pneumonia, cooking with gas reduced the risk by 46% compared with contaminated fuels, but increased the risk by 26% compared with electricity.
Gas fuels significantly reduce the risk of chronic lung diseases, including COPD and bronchitis, by 64%. Compared with polluting fuels, the risk of adverse pregnancy outcomes such as preterm birth and low birth weight is lower when cooking with gas (34% and 30% lower, respectively).
In addition, compared with electricity, gaseous fuel reduced the risk of wheezing by 58%, but did not significantly increase the risk of coughing. The risk of breathing difficulties from using natural gas is significantly reduced compared to polluting fuels.
This is the first study to systematically review the global health impacts of gaseous fuels (used for home cooking and heating). Unlike previous reviews, it considers a comprehensive range of health outcomes and assesses both pollution and clean (electricity) reference options.
In conclusion, switching from solid fuels or kerosene to clean gaseous fuels for cooking or heating can significantly reduce the risk of key health outcomes, thereby helping to reduce the global burden of disease caused by pollution. In low- and middle-income countries where the burden is highest, gaseous fuels (particularly LPG) are effective short- to medium-term options for scalable adoption. However, there is a slightly increased risk when using gaseous fuels compared to electricity.
Where feasible, electricity is likely to remain a priority for clean cooking, emphasizing the transitional role of gaseous fuels in areas without access to renewable electricity alternatives. The findings provide important evidence for clean energy policies at the national level, particularly in low- and middle-income countries, to effectively address the health burden associated with household air pollution.