Comparison of Respiratory Health Impacts Associated with Wood and Charcoal Biomass Fuels: A Population-Based Analysis of 475,000 Children from 30 Low- and Middle-Income Countries

Abstract

Background: The World Health Organisation reported that 45% of global acute respiratory infection (ARI) deaths in children under five years are attributable to household air pollution, which has been recognised to be strongly associated with solid biomass fuel usage in domestic settings. The introduction of legislative restrictions for charcoal production or purchase can result in unintended consequences, such as reversion to more polluting biomass fuels such as wood; which may increase health and environmental harms. However, there remains a paucity of evidence concerning the relative health risks between wood and charcoal. This study compares the risk of respiratory symptoms, ARI, and severe ARI among children aged under five years living in wood and charcoal fuel households across 30 low- and middle-income countries.

Methods: Data from children (N = 475,089) residing in wood or charcoal cooking households were extracted from multiple population-based Demographic and Health Survey databases (DHS) (N = 30 countries). Outcome measures were obtained from a maternal report of respiratory symptoms (cough, shortness of breath and fever) occurring in the two weeks prior to the survey date, generating a composite measure of ARI (cough and shortness of breath) and severe ARI (cough, shortness of breath and fever). Multivariable logistic regression analyses were implemented, with adjustment at individual, household, regional and country level for relevant demographic, social, and health-related confounding factors.

Results: Increased odds ratios of fever (AOR: 1.07; 95% CI: 1.02-1.12) were observed among children living in wood cooking households compared to the use of charcoal. However, no association was observed with shortness of breath (AOR: 1.03; 95% CI: 0.96-1.10), cough (AOR: 0.99; 95% CI: 0.95-1.04), ARI (AOR: 1.03; 95% CI: 0.96-1.11) or severe ARI (AOR: 1.07; 95% CI: 0.99-1.17). Within rural areas, only shortness of breath was observed to be associated with wood cooking (AOR: 1.08; 95% CI: 1.01-1.15). However, an increased odds ratio of ARI was observed in Asian (AOR: 1.25; 95% CI: 1.04-1.51) and East African countries (AOR: 1.11; 95% CI: 1.01-1.22) only.

Conclusion: Our population-based observational data indicates that in Asia and East Africa there is a greater risk of ARI among children aged under 5 years living in wood compared to charcoal cooking households. These findings have major implications for understanding the existing health impacts of wood-based biomass fuel usage and may be of relevance to settings where charcoal fuel restrictions are under consideration.

Keywords: acute respiratory infection; biomass fuel; household air pollution; low-and middle-income countries; respiratory symptoms.

Figure A1

Flow diagram for selection of final dataset for analysis from all household data sets available from the DHS program data archive [31] (a) Survey was excluded due to have low cell counts for wood or charcoal cooking (n = 31) included: Comoros 2012, Zimbabwe 2010–2011, Zimbabwe 2015, Senegal 2010–2017 (continuous dataset), Togo 2013–2014, Kyrgyz 2012, Tajikistan 2012, 2017, Papa New Guinea 2016–2017, Bangladesh 2011, 2014, Indonesia 2017, Maldives 2016–2017, Nepal 2011, 2016, Timor-Leste 2016, Albania 2017–2018, Armenia 2010, 2015–2016, Jordan 2012, Yemen 2012, Columbia 2010, 2015, Guatemala 2014–2015, Honduras 2011–2012, South Africa 2016, Namibia 2013, Lesotho 2014. (b) Surveys were excluded due to low cell counts with explanatory variable (n = 3) and low cell counts of missing entirely for wealth (n = 3) or three or more key variables (e.g., Breastfeeding, mode of delivery, household smoking) (n = 3). (c) Peru, Zambia and Kenya were excluded due to <50% missing data for breastfeeding. (d) Household smoking data was not collected for Kenya, Peru and the Philippines. (e) Chad, Ethiopia, Kenya, Guinea, Liberia, Afghanistan, Myanmar, Pakistan, Nigeria were excluded due to <50% missing data for birthweight.

Figure 1

Proportion of clean, kerosene, wood, charcoal, other biomass (dung, crop residue) fuel use within each country, ordered by geographical region.

Figure 2

Forest plot illustrating the adjusted odds ratio (AOR) for respiratory symptoms, ARI and severe ARI with wood cooking fuel compared to charcoal for all countries. The summary measure is adjusted for: age, birth order, mode of delivery, vitamin A supplementation, mother’s age, mother’s education level, wealth status, number of household members, rural/urban residence and location of cooking.