When Clean Water Meets Dirty Air: The Trade-Offs of Boiling Water with Solid Fuels

Song Wren

01-10-2025

Smoke flies out from the cave, even faintly, but it is enough to make Kingfisher squeamish and almost blackout.

In “A Shocking Secret”; Wild Wise Weird [1]

© Wallace Fonseca

For billions of people, the daily struggle for safe drinking water collides with another challenge: cooking with polluting fuels. Globally, 2 billion people lack safely managed drinking water, and 2.8 billion rely on solid fuels like wood and charcoal for cooking [2,3]. Boiling water is often promoted as a simple and effective household treatment to kill harmful microbes—but when done over smoky stoves, it may save lives from diarrhea while harming lungs and hearts.

A new modeling study published in Environmental Health Perspectives explored this trade-off by calculating health impacts from both cleaner water and dirtier air [4]. Researchers focused on Uganda and Vietnam, two countries where boiling water is common (82% and 91% of households, respectively) and where solid fuel use remains widespread [3,5,6]. They compared scenarios of different water contamination levels, boiling effectiveness, and stove types to estimate net health outcomes in terms of disability-adjusted life years (DALYs).

The results reveal a complex but encouraging picture. Boiling high-risk water generally reduced diarrheal disease burden significantly, by up to 1,100 DALYs and 367 DALYs per 10,000 people under and over age five in Uganda, respectively. Similar results are also observed in Vietnam, though with fewer avoided DALYs in children under 5 years of age. Even when done on smoky wood stoves, the health benefits of safer water often outweigh the added risks from household air pollution. However, the trade-off shifted under certain conditions: if water quality was already good, or if households boiled with highly polluting stoves without simultaneously cooking, then the health benefits could be offset by air pollution damage. By contrast, using clean stoves such as liquefied petroleum gas (LPG) or electric models nearly eliminated air pollution impacts, producing a strong net health benefit.

The study highlights the interconnectedness of water and air, nature and human health [7]. It demonstrates that solutions addressing one environmental risk can unintentionally worsen another—reminding us of the importance of integrated approaches. The findings also underscore the importance of cultivating ecological intelligence, which is the ability to perceive and act upon the profound connections between environmental conditions and human well-being. A higher NQ at the policy and household level means recognizing that clean water and clean air must be secured together, rather than traded off [8].

References

[1] Vuong QH. (2024). Wild Wise Weird. https://books.google.com/books?id=N10jEQAAQBAJ

[2] WHO (World Health Organization)/UNICEF. (2020). Progress on household drinking water, sanitation and hygiene. https://www.who.int/news/item/01-07-2021-billions-of-people-will-lack-access-to-safe-water-sanitation-and-hygiene-in-2030-unless-progress-quadruples-warn-who-unicef

[3] Stoner O, et al. (2021). Household cooking fuel estimates at global and country level for 1990 to 2030. Nature Communications, 12, 5793. https://doi.org/10.1038/s41467-021-26036-x

[4] Floess E, et al. (2025). Health trade-offs of boiling drinking water with solid fuels: A modeling study. Environmental Health Perspectives, 133, 06702. https://doi.org/10.1289/EHP15059

[5] Geremew A, Damtew YT. (2020). Household water treatment using adequate methods in Sub-Saharan countries: evidence from 2013–2016 demographic and health surveys. Journal of Water, Sanitation and Hygiene for Development, 10, 66-75. https://doi.org/10.2166/washdev.2019.107

[6] Rosa G, Clasen T. (2010). Estimating the scope of household water treatment in low- and medium-income countries. American Journal of Tropical Medicine and Hygiene, 82, 289-300. https://doi.org/10.4269/ajtmh.2010.09-0382.

[7] Nguyen MH. (2024). How can satirical fables offer us a vision for sustainability? Visions for Sustainability, 23(11267), 323-328. https://doi.org/10.13135/2384-8677/11267

[8] Vuong QH, Nguyen MH. (2025). On Nature Quotient. Pacific Conservation Biology, 31, PC25028. https://doi.org/10.1071/PC25028