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Indigenous forests prevent 15 million yearly cases of disease

A new study published in the journal Communications, Earth & Environment reveals that the Amazon rainforest and its Indigenous territories can absorb up to 26,000 metric tons of dangerous pollutants released by fires each year. This prevents thousands of cases of deadly respiratory and cardiovascular diseases and significantly reduces healthcare costs in some of the region’s most deforested cities.

The research team analyzed a decade of data and found that each hectare of burning forest costs cities at least US$2 million for treating associated illnesses. However, Indigenous forests can prevent an estimated 15 million cases of respiratory and cardiovascular disease every year, which would otherwise cost the healthcare system US$2 billion. Additionally, heavily forested Indigenous lands are protecting urban and rural populations in the “arc of deforestation,” the southeastern region of the rainforest that has lost the most forest cover to agroindustry and other legal and illegal activities.

“Worldwide, forests are known for absorbing pollutants from fires through pores on the surface of the leaves, but this is the first time we have estimated the capacity of tropical forests to do this,” said study lead author Dr. Paula Prist, a research scientist at the EcoHealth Alliance. “Our results indicate that the Amazon rainforest can absorb as much as 26,000 metric tons of the particles every year, and Indigenous territories are responsible for 27% of this absorption, while covering only 22 percent of the rainforest.”

The findings were released just days before President Lula completes his first 100 days in office. The study could add urgency to the Brazilian leader’s promise to recognize and enforce the land rights of Indigenous peoples, already proven to play an outsize role in reducing the deforestation and biodiversity loss in the Amazon.

Study co-author Dr. Florencia Sangermano is an expert in the use of geospatial analysis and satellite remote sensing to evaluate changes in the earth system, and to assess their effect on ecosystems and biodiversity.

“Science has shown that Indigenous-managed forests suffer less deforestation that drives climate change and pandemic risk, but this is the first effort to quantify how they benefit human and economic health, indicating that the benefits go far beyond the borders of these territories,” said Dr. Sangermano.

The researchers focused their analysis on the Brazilian Legal Amazon, an area that covers more than half the Brazilian territory, including 722 towns and cities. During the fire season, from the end of July through November, the region becomes “among the most polluted places on earth,” noted Dr. Prist and her co-authors.

Forest fires in tropical forest countries are responsible for 90 percent of global emissions of the particulate matter released by fires, including those in the Amazon basin. The evergreen broadleaf forests of the Amazon are more likely than forests in other biomes to release black and organic carbonaceous aerosols, the primary components of the fine particulate matter implicated in the rising rate of respiratory and cardiovascular diseases in the region.

The report also highlights that fires in the Amazon consumed 519,000 hectares of forest between May 19 and October 31, 2021, with Brazil losing the most forest cover to fires. Prist said, “The number of fires has been increasing in the last few years, and in 2020, deforestation rates reached the highest levels of the decade in the Brazilian Amazon.”

Previous studies have demonstrated that Indigenous communities’ management of land is safeguarding significant forested regions from wildfires. They also concluded that the Amazon rainforests are shielding nearby areas from smoke damage while simultaneously protecting neighboring communities. The recent research delves deeper by examining the pollutants’ potential to travel over long distances and the rainforest’s ability to soak them up. The study’s authors concluded that Indigenous territories may be supplying health and economic advantages to populations residing up to 500 kilometers away from where the fires are occurring.

“Our results suggest there is a need to act now – in advance of the fire season – to protect Indigenous peoples and their forests as a matter of public health,” said Dr. Prist. “Failure to recognize and enforce the land rights of Indigenous peoples in the Amazon could lead to deforestation of their lands and an increase in the number of reported infections, as well as a significant rise in health care costs, particularly in already deforested areas.”

Currently, just five Indigenous territories in the Brazilian Legal Amazon, mainly situated in the densely forested western region of the Brazilian Amazon, account for eight percent of the rainforest’s ability to absorb particles from forest fires. Currently, there are 383 recognized Indigenous territories in the Brazilian Legal Amazon, spanning over 1,160,000 square km.

Based on a decade’s worth of reports of respiratory and cardiovascular diseases across the Amazon, along with data on pollutants and forest cover, the scientists identified two million cases of respiratory and cardiovascular diseases. The study traced these cases to an estimated 1.7 metric tons of particles released annually by fires during the dry season, which typically commences in late July. This suggests that if the rainforest is damaged, it could lead to a higher quantity of pollutants and greater rates of disease.

The scientists relied solely on satellite data to quantify emissions from fires as precise meteorological data was lacking. The fires are frequently set intentionally to illegally clear land for crops or pasture. The researchers did not calculate the rainforest’s actual removal rates; instead, they estimated the Amazon’s capacity to absorb the particles released by fires during the dry season. They made assumptions based on studies conducted in temperate regions.

“Despite the challenges, we were able to evaluate the contribution of the Amazon forest and the Indigenous territories to the maintenance of human health, and the economic benefits that its conservation can bring,” said Dr. Sangermano. “Our numbers probably underestimate the ecosystem services provided by the Amazon rainforest and its Indigenous territories because there are no calculations for the pollutant absorption rates of tropical trees.”

The study reveals the crucial role of Indigenous territories in absorbing dangerous pollutants and preventing respiratory and cardiovascular diseases, which could significantly reduce healthcare costs in the region. The research provides additional evidence to support the recognition and enforcement of Indigenous land rights in the Amazon, which can help prevent further deforestation.

Why is the Amazon rainforest so important?

The Amazon Rainforest, also known as the “Lungs of the Earth,” is the world’s largest tropical rainforest, spanning over 6.7 million square kilometers across nine South American countries. It is home to an estimated 40,000 plant species, 2.5 million insect species, and more than 2,000 species of birds and mammals. The Amazon Rainforest plays a vital role in regulating the Earth’s climate, maintaining global biodiversity, and providing essential ecosystem services to humans.

Regulation of the Earth’s Climate

The Amazon Rainforest is often referred to as the “Lungs of the Earth” because of its ability to absorb carbon dioxide from the atmosphere and produce oxygen through photosynthesis. The rainforest is estimated to absorb approximately 2 billion tons of carbon dioxide annually, which helps to regulate the Earth’s climate by reducing the concentration of greenhouse gases in the atmosphere. The Amazon also plays a critical role in regulating the Earth’s water cycle by releasing moisture into the atmosphere through a process called evapotranspiration. This process helps to maintain global rainfall patterns and prevents droughts in other parts of the world.

Maintaining Global Biodiversity

The Amazon Rainforest is one of the most biodiverse regions on the planet, with an estimated 16,000 tree species alone. The region is home to many iconic species, such as jaguars, sloths, anacondas, and macaws. However, many of these species are endangered due to deforestation, climate change, and human activities. The loss of these species not only has a significant impact on the rainforest’s ecosystem but also on the wider global biodiversity. The Amazon is a vital component in maintaining the world’s biodiversity, and the loss of the rainforest could have severe consequences for the planet’s ecosystems.

Providing Essential Ecosystem Services to Humans

The Amazon Rainforest provides numerous ecosystem services that are essential to human well-being. These services include regulating the climate, purifying the air and water, providing food and medicine, and supporting economic activities such as tourism and agriculture. The rainforest’s biodiversity is a significant source of medicine, with approximately 25% of modern medicine derived from rainforest plants. Additionally, the Amazon is a crucial source of food for many indigenous communities, providing fish, fruits, and nuts.

The Amazon also plays a crucial role in supporting global agriculture, with approximately 80% of the world’s soybeans and 40% of the world’s beef coming from the region. However, the continued expansion of agriculture and ranching into the Amazon Rainforest is causing significant deforestation, which threatens the region’s ecosystem services and the livelihoods of local communities.

In summary, the Amazon Rainforest is one of the most important ecosystems on the planet, providing essential ecosystem services to humans and maintaining global biodiversity. The rainforest’s role in regulating the Earth’s climate, providing food and medicine, and supporting economic activities cannot be overstated. However, the Amazon Rainforest is under threat from deforestation, climate change, and human activities. It is essential that we take action to protect this vital ecosystem and ensure that it continues to provide essential ecosystem services to humans and maintain global biodiversity for generations to come.


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