Living in Watersheds with More Trees Reduces Disease Risk

Diarrheal disease from contaminated water is the second leading cause of death among children under the age of five, claiming more than 360,000 lives annually. Now, a new study of children in 35 countries finds that those living in a watershed with more trees had a lower risk of contracting the illness.

The research, published in the journal Nature Communications, found that a 30 percent increase in upstream tree cover in some rural areas is just as effective at reducing disease risk as having improved sanitation, such as indoor plumbing or toilets. The research analyzed health, demographic, and geospatial data for 300,000 children.

“We are not saying trees are more important than toilets and indoor plumbing,” co-author of the study Diego Herrera, an economist at the Environmental Defense Fund who conducted the research while a postdoctoral researcher at the University of Vermont, said in a statement. “But these findings clearly show that forests and other natural systems can complement traditional water sanitation systems, and help compensate for a lack of infrastructure.” 

The researchers argue that dense tree coverage upstream helped filter or dilute pollutants before they reached communities, as well as deterred human activity that could pollute the waterways, such as agriculture or infrastructure development.