In places without access to electric cooking and heating options, the use of gaseous fuels over polluting solid fuel and kerosine can significantly reduce adverse respiratory health outcomes, according to study findings published in The Lancet Respiratory Medicine.
Researchers conducted a systematic review and meta-analysis to synthesize global evidence on the respiratory health effects of gaseous fuels (ie, natural gas, liquefied petroleum gas, and biogas), assessing the health effects of these fuels compared with clean fuel (ie, electricity) and polluting fuels (ie, solids and kerosene).
Multiple databases were searched from January 1, 1980, to the date of the search, which ranged from December 16, 2020, to February 6, 2021. Eligible studies reported on cooking, heating, or both, as well as any gaseous or liquid fuel and any health effect or symptom.
In the meta-analyses, health outcomes and symptoms were grouped into 5 categories: asthma; acute lower respiratory infections; chronic lung disease; respiratory symptoms; and adverse pregnancy.
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For LMICs reliant on polluting solid fuels and kerosene, transitions to gaseous fuels for cooking or heating can potentially produce substantial health benefits.
The meta-analyses included 116 studies from 34 countries, with (2%) randomized controlled trials, 13 (11%) case-control studies, 23 (20%) cohort studies, and 78 (67%) cross-sectional studies.
Asthma was evaluated in children, adults, or both in 46 studies (49 estimates). Compared with polluting fuels, gas use for cooking or heating did not appear to change the estimated risk for asthma in children (odds ratio [OR], 1.04; 95% CI, 0.70-1.55; P =.84). Adults had a 35% lower risk for asthma (OR, 0.65; 95% CI, 0.43-1.00; P =.052; 6 studies).
Use of gas for cooking or heating was not associated with an increased risk estimate for asthma compared with electricity among children (OR, 1.09; 95% CI, 0.99-1.19; P =.071; 20 studies) or adults (OR, 1.43; 95% CI, 0.90-2.27; P =.13; 5 studies).
Use of gas for cooking compared with polluting fuels significantly reduced the risk for acute lower respiratory infections or pneumonia by 46% (OR, 0.54; 95% CI, 0.38-0.77; P =.00080; 7 studies). However, cooking with gas compared with electricity increased the risk of acute lower respiratory infections or pneumonia by 26% (n=6: OR, 1.26; 95% CI, 1.03-1.53; P =.025).
A statistically significant (P <.05) decreased risk was observed for all chronic lung disease conditions when using gas for cooking or heating vs polluting fuels, ranging from a decrease of 40% for bronchitis to 73% for pulmonary function deficit and severe respiratory illness or death. The pooled result for all chronic lung disease conditions showed a statistically significant reduced risk of 64% (OR, 0.36; 95% CI, 0.27-0.48; P <.0005).
In 7 studies that compared use of gas to electricity for cooking or heating on chronic lung disease outcomes, a small but statistically significant increased risk for chronic obstructive pulmonary disease (COPD; 15%) was found for cooking or heating with gas vs electricity (n=3: OR, 1.15; 95% CI, 1.06-1.25; P = .0011). A small but significantly reduced risk (13%) was found for bronchitis (n=4: OR, 0.87; 95% CI, 0.81-0.93; P <.0001).
A statistically significant decreased risk for preterm birth (OR, 0.66; 95% CI, 0.45-0.97; P =.033; 3 studies) and low birth weight (OR, 0.70; 95% CI, 0.53-0.93; P =.015; 7 studies) was found for using gas for cooking compared with polluting fuels.
A total of 40 studies assessed cooking or heating with gas vs polluting fuels (n=16) or electricity (n=24) and self-reported wheeze, with a statistically significant reduced risk of 58% when using gas for cooking vs polluting fuels (OR, 0.42; 95% CI, 0.30-0.59; P <.0001).
Among 32 studies that assessed cooking or heating with gas and self-reported cough, with 18 estimates that included a polluting reference fuel and 17 that included electricity, cooking with gas (and in 1 study, heating with gas) was associated with a significant 56% reduced risk for cough vs polluting fuels (OR, 0.44; 95% CI, 0.32-0.62; P <.0001).
Limitations include use of data from observational studies and the pooling of effect estimates from heterogeneous epidemiologic studies with varying methods.
“This study shows a lower risk for key health outcomes when switching from polluting solid fuels and kerosene to use of clean gaseous fuels for cooking or heating. Our study also identifies a modest increase in risk from use of gaseous fuels compared with electricity for a few health outcomes,” said the study authors. “For LMICs reliant on polluting solid fuels and kerosene, transitions to gaseous fuels for cooking or heating can potentially produce substantial health benefits,” said study authors. They added that transitioning to electricity would likely offer greater health protection in places where this option is scalable and accessible.
