Deforestation of Amazônia is increasing pollution in South American countries
Elton Alisson/Agência FAPESP/DICYT The Amazon states of Pará, Rondônia, Amazonas and Acre have "exported" the smoke produced by burning to clear land to Bolivia, Peru and Paraguay and have contributed to increasing the levels of atmospheric pollution in these neighboring countries. Along with Mato Grosso, these four states have also registered the highest number of wildfires in South America.
The observation is from a study carried out by researchers from the National Institute for Space Research (INPE) using the Tupã supercomputer installed at the institution, with resources from FAPESP and the Ministry of Science, Technology and Innovation (MCTI).
Several of the study findings were presented in a lecture about the tri-national impact of biomass burning and southwestern Amazon smoke during the 66th Annual Meeting of the Brazilian Society for the Advancement of Science (SBPC) on the campus of the Federal University of Acre (UFAC) in Rio Branco, which ended July 27, 2014.
“The largest amount of smoke from forest burning in South America comes from Brazil. Brazil actually exports smoke and pollutes other countries in the region,” Saulo Ribeiro de Freitas, an INPE researcher, told Agência FAPESP.
According to Freitas, forest burning is occurring on a global scale. In South America, however, more than 5,000 hotspots are being reported in a single day.
During a single month, the accumulation of several hotspots generates smoke plumes. Carried by air masses produced in Brazil’s northern and central regions, these smoke plumes travel to the southern region of South America and can cover areas of up to 5 million square kilometers, as seen in satellite imagery.
“The type of air circulation prevalent in the dry season in northern Brazil causes there to be an export corridor that channels the smoke produced by the region’s fires to western South America, invading Peru, Bolivia and Paraguay,” Freitas says.
“This corridor often reaches Argentina as well and is only blocked when a cold front comes through that can take the smoke that comes from the north of Brazil and return it. When this inversion occur, it is possible to see the columns of smoke passing over the city of São Paulo,” he said.
In an effort to estimate the sources of the smoke emissions from hotspots in Amazonia and indicate the relative contribution of each Amazon state and country in this emission, the researchers have developed a system in the past two years based on satellite data and numerical (computer) modeling.
The system is able to identify where the South American hotspots are and to estimate the quantity of smoke and, as a result, the air pollutants emitted in each of the Brazilian states or countries in this region.
Emissions in Acre
The system was used to identify the sources of pollutant emissions from fires, such as particulate matter in air or atmospheric aerosols, in the state of Acre in 2005, 2008, 2009 and 2010.
Some of the simulations determined that between 5 and 10 days per year, the air in the state presented an average concentration of atmospheric aerosols with diameters above 2.5 microns (µg) – which are considered to be most important in terms of health impacts – in the range between 40 and 80 microns per cubic meter (µg/m³). This size is above the limits considered tolerable by the World Health Organization (WHO).
During the dry season between July and November, the air in Acre remains in this same range, at levels of an average concentration of particulate matter of 2.5 µg, for up to 30 days.
During the 2005 dry season, for example, when emissions from fires in Acre were very high, the monthly average emissions of particulates from biomass burning in the state reached 90 µg/m³. “We determined these same variations in the state’s air quality during the simulated four years of the study,” Freitas explained.
The researchers also calculated the percentage of atmospheric pollution produced by the smoke from biomass burning coming from Acre itself and from the neighboring states and countries.
The results of the calculations indicated that, for example, the largest contributors in August 2005 to emissions of smoke from biomass burning were from the state of Acre itself, followed by the state of Amazonas. By November of that same year, most of the emissions had come from Amazonas and Pará.
The same pattern of sources of smoke emission from burning in the region was observed in the four years of simulations, according to Freitas. “The largest focal point for smoke emission reported in Acre is in Brazil itself. The results of our simulations clearly show this,” he said.
The study was carried out by INPE researchers in collaboration with colleagues from UFAC at the request of the Acre State Attorney’s Office.
As a result of the health problems experienced by the population due to the increase in hotspots in the state in 2005, the agency filed a civil action in 2007 calling for a ban on the use of fire for land clearing in the region and asked that the two institutions conduct a technical study to identify the sources of pollution from fires in the state.
“One of the allegations was that most of the smoke from burning was not emitted here in the state but from neighboring countries, specifically Bolivia and Peru. We appealed to INPE and UFAC to determine whether it was possible to identify the origin of the smoke from the burning in the state,” said Patricia Rego, Attorney General of Acre’s State Attorney’s Office.
The study findings indicated a very remote possibility that the smoke produced by biomass burning in Bolivia would invade Acre.
“One of the only hypotheses for this would be if cold fronts from southern South America carried the polluted air from that region to northern Brazil. But that type of occurrence is very rare,” Freitas said.
Professor José Montanez Montaño from the Universidad Autónoma Gabriel René Moreno (UAGRM) in Santa Cruz de La Sierra, in Bolivia, pointed out during the conference that because the problem of biomass burning and smoke in southwestern Amazônia is cross-border, Brazil, Bolivia and Peru need to draft trinational legislation to identify and eliminate the causes.
“Brazil emits the most smoke, but the problems caused by biomass burning are felt equally across the three countries. Because we are the recipients of this smoke and not the senders, we are obviously more affected,” Montaño said.