According to the World Health Organization (WHO), diarrheal disease is one of the leading causes of death for children around the world, annually killing more than half a million children under the age of five. Though over 1.5 billion cases of pediatric diarrheal disease occur each year, it is an entirely preventable disease when communities have access to clean water and adequate sanitation. It turns out that there may be a surprisingly simple solution: trees clean water.
How Do Trees Clean Water?
A new study published in Nature has concluded that the presence of trees upstream from a community reduces the risk of diarrheal disease (a major cause of child deaths worldwide) among children and helps keep the water clean.
Using data from 35 countries, researchers compared health records from nearly 300,000 children to socioeconomic factors and watershed conditions to determine how forested ecosystems affect public health. Watersheds are terrestrial areas that streams, rivers, lakes, or aquifers service. The authors of the study found that trees significantly affect the quality of water and sanitation in watersheds, contributing to a lower incidence of diarrheal disease among children in rural communities.
These findings support previous research chronicling the deleterious health effects of forest loss on children. Children living in communities that experienced tree cover loss were more likely to suffer diarrheal disease than children residing in watersheds with no net forest loss and were also between 20 and 30 percent less likely to have a diverse and nutritious diet.
Why Rural Models Matter
Rural households use untreated surface water — rivers, lakes, ponds, and irrigations canals — at a rate disproportionate to urban household use.
A resounding majority of communities who use surface water reside in rural areas, reflecting a lack of access to modern water systems; only 33% of the rural regions are served by piped water sources, according to examinations that the study’s authors cited. As such, these communities are particularly vulnerable to public health issues stemming from water quality, reports Nature.
Though rural communities around the globe are directly affected by the quality of surface water, nearly two-thirds of the American public is concerned about the pollution of their drinking water, according to a Gallup poll released last spring.
Each watershed faces different challenges, but these challenges typically stem from human use, whether in the form of contamination from farming, livestock, or industrial practices that are detrimental to the health of communities living downstream.
The Power of Trees
Forests and wetlands are vast filters of pollutants and pathogens. In rural communities, if these ecosystems are large enough, they can serve as a natural system of sanitation.
The researchers of the Nature study determined that a 30 percent increase in tree cover upstream from a community had benefits similar to improvements in sanitation facilities (such as indoor plumbing or the installation of toilets), both of which resulted in a four percent reduction in diarrheal disease rates. Based on projections, the prevalence of tree cover is inversely related to the incidence of diarrheal disease.
In contrast, education and wealth each reduced the probability of diarrheal disease by approximately twelve percent. Although education and wealth proffer even more significant benefits than trees upon a rural community, the capital required to access these resources might not be available in developing nations, or even in rural regions of developed countries as a way to mitigate preventable childhood fatalities.
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