Healthy forests are more than climate shields; in the Amazon, they also serve as public-health infrastructure.

A Communications Earth & Environment study spanning two decades across the biome links the extent and legal status of Indigenous Territories to 27 respiratory, cardiovascular, and zoonotic or vector-borne diseases. The findings are complex, but one pattern is clear: Where surrounding forest cover is high and fragmentation is low, Indigenous lands help blunt health risks.

Between 2001 and 2019, the Amazon logged 28 million cases of illness, four-fifths of them from fires and mostly respiratory. More than 532,000 square kilometers burned during that period, with most blazes starting outside Indigenous lands. Each surge in fire activity sent fine particulate pollution (PM2.5) higher, and with it hospital visits for asthma, bronchitis and other respiratory ailments.

Landscape context matters. Municipalities with high forest cover outside Indigenous lands see fewer fire-related illnesses, as those forests buffer PM2.5 exposure. The protective effect appears once overall cover exceeds about 45%. For zoonotic and vector-borne diseases, forests inside and outside Indigenous lands offset fragmentation when combined cover passes 40%. Fragmentation weakens these protections.

Law matters too. Recognized Indigenous Territories show a nonlinear pattern: at low to mid coverage they correlate with higher incidence, but at higher coverage with lower incidence. Unrecognized territories are consistently tied to worse outcomes, reflecting heavier fire and deforestation where rights are weak.

“Indigenous forests in the Amazon bring health benefits to millions,” said Paula Prist of the International Union for Conservation of Nature in a statement. “We have long known that the rainforest is home to medicinal plants and animals that have cured countless illnesses. This study offers new evidence that forests themselves are a balm for fire-related threats to people’s lungs and hearts, to illnesses like Chagas, malaria and spotted fevers. Ensuring Indigenous communities have strong rights over their lands is the best way to keep forests and their health benefits intact.”

As fire season returns and climate talks convene in Belém, the message is straightforward: securing Indigenous land rights and conserving contiguous forests is a health intervention as well as a climate one.