Amazon deforestation data are used as a gauge, at the national and international levels, to indicate the current situation of the political management of the control of and combat against this process, which is usually widely disseminated in the media. Due to the weakening of environmental policies in recent years, there was a forecast that deforestation for the year 2020 ¹1. Silva Junior CHL, Pessôa ACM, Carvalho NS, Reis JBC, Anderson LO, Aragão LEOC. The Brazilian Amazon deforestation rate in 2020 is the greatest of the decade. Nat Ecol Evol 2021; 5:144-5. would be the highest of the decade, above that of 2019, which exceeded 10,800km²¹1. Silva Junior CHL, Pessôa ACM, Carvalho NS, Reis JBC, Anderson LO, Aragão LEOC. The Brazilian Amazon deforestation rate in 2020 is the greatest of the decade. Nat Ecol Evol 2021; 5:144-5., the highest rate since 2008. Although 2020 had a slightly lower rate than 2019, deforestation in 2021 and 2022 exceeded 12,000km²²2. Coordenação-Geral de Observação da Terra, Instituto Nacional de Pesquisas Espaciais. Monitoramento do desmatamento da Floresta Amazônica brasileira por satélite. http://www.obt.inpe.br/OBT/assuntos/programas/amazonia/prodes (accessed on 10/Jul/2023).
http://www.obt.inpe.br/OBT/assuntos/prog... , which again featured prominently in global media. Recently, the Yanomami crisis revealed another growing threat to Amazonian life: the push of mining activities in the region. Estimates point to increased mining rates mainly after 2010, and 2020 data showed that the total mining area exceeded the industrial mining area ³3. MapBiomas. Coleção [versão 7.1] da Série Anual de Mapas de Cobertura e Uso da Terra do Brasil. https://mapbiomas.org/ (accessed on 10/Jul/2023).
https://mapbiomas.org/... . The negative impacts - beyond social and cultural ruptures caused to indigenous peoples - include increased disease rates, environmental contamination, and food insecurity ⁴4. Codeço CT. CSP starts a Thematic Section dedicated to the Amazon. Cad Saúde Pública 2023; 39:e00023223..

The advance of deforestation reveals a small part of the socio-environmental problem related to the Amazonian forests. A recent study ⁵5. Lapola DM, Pinho P, Barlow J, Aragão LEOC, Berenguer E, Carmenta R, et al. The drivers and impacts of Amazon forest degradation. Science 2023; 379:eabp8622. quantified that fire, forest fragmentation and logging between 2001 and 2018 have already impacted more than 5.5% of the forests in the entire Amazon basin, and this extension corresponds to 112% of the total area deforested in that period. If we add to this list of forest degradation vectors the occurrence of extreme droughts, the area increases to 38% of the remaining Amazonian forests.

It is widely known that fire is the main instrument for disposing of biomass after clear-cutting the forest, and that it causes a series of negative socioeconomic and environmental impacts. For example, on the global scale, greenhouse gas emissions from slash-and-burn practices and wildfires directly affect the rainfall and temperature regime and, on the regional scale, directly generate air pollution, thus affecting air quality ⁶6. Reddington CL, Butt EW, Ridley DA, Artaxo P, Morgan WT, Coe H, et al. Air quality and human health improvements from reductions in deforestation-related fire in Brazil. Nat Geosci 2015; 8:768-71.^,77. Aragão LEOC, Anderson LO, Fonseca MG, Rosan TM, Vedovato LB, Wagner FH, et al. 21st century drought-related fires counteract the decline of Amazon deforestation carbon emissions. Nat Commun 2018; 9:536.. Locally, the negative impacts of fires include the degradation of soils and forests, the imposition of restrictions and losses on those who depend on them, affecting their properties, public infrastructure or even services ⁸8. Anderson LO, Trivedi M, Queiroz J, Aragão L, Marengo J, Young C, et al. Counting the costs of the 2005 Amazon drought: a preliminary assessment. Ecosystem services for poverty alleviation in Amazonia. https://www.researchgate.net/publication/290379571_counting_the_costs_of_the_2005_amazon_drought_a_preliminary_assessment (accessed on 10/Jul/2023).
https://www.researchgate.net/publication... . However, it is much less known that areas with forest fragmentation ⁹9. Silva-Junior CHL, Buna ATM, Bezerra DS, Costa OS, Santos AL, Basson LOD, et al. Forest fragmentation and fires in the Eastern Brazilian Amazon - Maranhão State, Brazil. Fire 2022; 5:77., logging ¹⁰10. Berenguer E, Ferreira J, Gardner TA, Aragão LEOC, De Camargo PB, Cerri CE, et al. A large-scale field assessment of carbon stocks in human-modified tropical forests. Glob Chang Biol 2014; 20:3713-26., and forest areas that have already been affected by fire are more susceptible to new fires ¹¹11. Brando PM, Balch JK, Nepstad DC, Morton DC, Putz FE, Coe MT, et al. Abrupt increases in Amazonian tree mortality due to drought-fire interactions. Proc Natl Acad Sci U S A 2014; 111:6347-52.. Moreover, extreme droughts, which have intensified and become more recurrent due to climate change ¹²12. Ribeiro GG, Anderson LO, Barretos NJC, Abreu R, Alves L, Dong B, et al. Attributing the 2015/2016 Amazon basin drought to anthropogenic influence. Climate Resilience and Sustainability 2022; 1:e25., amplify the extent and magnitude of fires ⁷7. Aragão LEOC, Anderson LO, Fonseca MG, Rosan TM, Vedovato LB, Wagner FH, et al. 21st century drought-related fires counteract the decline of Amazon deforestation carbon emissions. Nat Commun 2018; 9:536.. This means that even if deforestation rates are controlled, there are still all the other forcings that lead to the occurrence of fires present in human practices and Amazonian landscapes ¹³13. Aragão LEOC, Shimabukuro YE. The incidence of fire in Amazonian forests with implications for REDD. Science 2010; 328:1275-8., and these have increased over this century ¹⁴14. Silveira MVF, Silva-Junior CHL, Anderson LO, Aragão LEOC. Amazon fires in the 21st century: the year of 2020 in evidence. Glob Ecol Biogeogr 2022; 31:2026-40..

The exposure of the population to smoke has several implications, both in the short and long terms, ranging from allergic-respiratory crises to cancer, impacting mainly children and the elderly. Smoke from slash-and-burn practices and forest fires is generally composed both of primary pollutants - such as particulate matter (PM), carbon monoxide (CO), nitrogen oxides (NOx), and non-methane organic compounds (NMOC) - and precursors of secondary pollutants, which include ozone (O₃) and other secondary organic aerosols (SOA) ¹⁵15. Reisen F, Duran SM, Flannigan M, Elliott C, Rideout K. Wildfire smoke and public health risk. Int J Wildland Fire 2015; 24:1029-44.. Several studies have demonstrated the relation between fine particulate matter (PM_2.5) and increased hospital admissions due to respiratory problems in the Amazon region ¹⁶16. Hacon SS, Gonçalves KS, Barcellos C, Oliveira-da-Costa M. Amazônia brasileira: potenciais impactos das queimadas sobre a saúde humana no contexto da expansão da COVID-19. https://wwfbr.awsassets.panda.org/downloads/nota_tecnica_covid_x_queimadas_na_amazonia_arquivo_fiinal.pdf (accessed on 10/Jul/2023).
https://wwfbr.awsassets.panda.org/downlo... ^,1717. Campanharo WA, Morello T, Christofoletti MAM, Anderson LO. Hospitalization due to fire-induced pollution in the Brazilian Legal Amazon from 2005 to 2018. Remote Sens (Basel) 2022; 14:69..

However, it should be noted that studies quantifying the impact of air pollution from slash-and-burn agriculture and fires face methodological challenges. The first refers to the detection of atmospheric aerosols, their dispersion in space, in the air column, and in time, as the duration of exposure of people in number of hours, days, weeks, etc. On the other hand, the search for these relations with cases of the number of people affected, usually attributed to the number of deaths and hospitalizations due to respiratory problems, are underestimated, either in the short-term time scale, due to the lack of registration of the number of people who seek self-medication to treat symptoms, or the problems of lack of health care units or difficult access. Records of outpatient care are limited, and in general only hospitalizations are counted, and in the long-term time scale, there is a bottleneck in studies that quantify cases in which recurrent exposure to pollutants can lead to the development of cancer, and that long-term exposure to smoke can reduce life expectancy by more than two years ¹⁸18. Ebenstein A, Fan M, Greenstone M, He G, Zhou M, Chen S, et al. New evidence on the impact of sustained exposure to air pollution on life expectancy from China's Huai River Policy. Chicago: Becker Friedman Institute for Research in Economics, The University of Chigaco; 2017. (Working Paper Series, 2017-11).. It is estimated that, only between June and October 2019, the cost of hospitalizations in the Brazilian Unified National Health System (SUS) in the Amazon region associated with fires was approximately BRL 2.6 million ¹⁹19. Sant'anna AA, Rocha R. Impactos dos incêndios relacionados ao desmatamento na Amazônia brasileira sobre saúde. https://ieps.org.br/wp-content/uploads/2021/11/NT11_Amazon_pt-vf.pdf (accessed on 07/Jul/2023).
https://ieps.org.br/wp-content/uploads/2... , which excludes all other economic impacts, whether on the lives of the people who were hospitalized, which may compromise their income, but also on the entire production of goods and provision of services compromised by the illness of the population.

One of the main important aspects to be considered, both to measure and attribute responsibility for the impacts of fires on air quality, and to establish technical and political guidelines to foster a culture of risk perception as to exposure to them, refers to the availability of near real-time monitoring data. However, there is a lack of resources for the purchase and maintenance of sensors, as well as to establish and operate air quality monitoring networks throughout the country. A survey ²⁰20. Vormittag EMPAA, Cirqueira SSR, Wicher Neto H, Saldiva PHN. Análise do monitoramento da qualidade do ar no Brasil. Estud Av 2021; 35:7-30. published in 2021 showed that only ten states and the Federal District monitor air quality, with a network of 371 sensors, 80% of which are located in the Southeastern region of the country. This data gap leads to a situation of unpredictability as there are no quantitative bases so as to understand the magnitude of this growing problem. Technological advances in the development of low-cost sensors have been presented as an alternative, both for monitoring air quality and as a strategy for citizen science and social engagement ²¹21. Lu T, Liu Y, Garcia A, Wang M, Li Y, Bravo-villasenor G, et al. Leveraging citizen science and low-cost sensors to characterize air pollution exposure of disadvantaged communities in Southern California. Int J Environ Res Public Health 2022; 19:8777..

An initiative that contributed to advances in the understanding of seasonality and human exposure to smoke was the network of low-cost sensors integrated with the Internet of Things (IoT) for on-site monitoring of particulate matter, started in the state of Acre and then expanded to Peru and Bolivia ²²22. Brown IF, Fonseca Duarte A, Torres M, Ascorra C, Reyes JF, Rioja-Ballivián G, et al. Monitoramento de fumaça em tempo real mediante sensores de baixo custo na Amazônia sul-ocidental. In: Anais do XIX Simpósio Brasileiro de Sensoriamento Remoto. São José dos Campos: Instituto Nacional de Pesquisas Espaciais; 2019. https://proceedings.science/sbsr-2019/trabalhos/monitoramento-de-fumaca-em-tempo-real-mediante-sensores-de-baixo-custo-instalado?lang=pt-br.
https://proceedings.science/sbsr-2019/tr... . Another innovative aspect of this monitoring network was the partnership established between researchers and the Public Prosecutor’s Office of the state of Acre, which enabled the expansion of the network to the other states of the Brazilian Amazon ²³23. Vormittag EMPAA, Wicher Neto H, Rodrigues PF, Lima B. Iniciativa Acre de Monitoramento da Qualidade do Ar: implementação e impactos de uma rede de monitoramento do ar com equipamentos de baixo custo. São Paulo: Instituto Saúde e Sustentabilidade; 2021.. This quantitative data collection network for the state of Acre showed that, between 2019 and 2022, only in the municipality of Brasiléia there was an annual average of 77 days with higher particulate matter concentration in the air than that established by the World Health Organization (WHO): 15μg/m³ in 24 hours. Other nine municipalities located in Acre also presented an annual average of more than two months of exposure to this type of pollution during this period ²⁴24. Laboratório de Geoprocessamento Aplicado ao Meio Ambiente. Qualidade do ar no Acre. http://www.acrequalidadedoar.info/ (accessed on 10/Jul/2023).
http://www.acrequalidadedoar.info/... . This critical diagnosis shows that 19 of the 22 municipalities in Acre had, on average, more than 30 days with values harmful to health. For the urban perimeter and surroundings of the city of Rio Branco, it was estimated that the adoption of a zero-hectare limit for slash-and-burn areas would result in avoiding 1,393 cases of hospitalizations due to acute respiratory diseases per year during the peak slash-and-burn months ²⁵25. Morello T, Silva R, Silva S, Duarte A, Maciel R, Moreira D, et al. Queimadas e saúde: uma análise do caso de Rio Branco, Acre. In: Anais do XIX Simpósio de Sensoriamento Remoto. São José dos Campos: Instituto Nacional de Pesquisas Espaciais; 2019. p. 199-202..

Pollution from slash-and-burn practices and forest fires is not an isolated factor. Since the first months of 2020, the COVID-19 pandemic has added another factor threatening the world and especially the Amazon region, where several social and environmental vulnerabilities are significant in relation to other regions of the country. For example, the mortality rate of indigenous people infected with the coronavirus was estimated to be about 150% higher than the Brazilian average, showing a greater vulnerability of this population ²⁶26. Instituto Socioambiental. COVID-19 e os povos indígenas. https://covid19.socioambiental.org/ (accessed on 10/Jul/2023).
https://covid19.socioambiental.org/... . In January 2021, the collapse of the health care system in Manaus was staggering, with hospitals lacking oxygen and patients moved to other states, cemeteries with no space for new graves, and mass graves dug with backhoes, revealing unprecedented political and institutional vulnerability. Amid this situation, an external threat is added: in February 2021 a great flood begins in the west of the Amazon, flooding the state of Acre and reaching the central region of the Amazon, in Manaus, in June of the same year. This conjuncture is an example of how compound threats, such as COVID-19 and flooding, or COVID-19 and wildfires, can intensify the risks of each of these factors in isolation, thus amplifying the health risks in all cases.

However, in this recipe for socio-environmental construction of multi-threats to human health, we can still put more ingredients. Observational data show a rainfall reduction of 34% in the east and 20% in the west of the Amazon during the dry season months compared to 40 years ago. Temperature data show an increase for the same season and period ranging between 2.5ºC in the south of the biome, 1.7ºC in the west and 1.9ºC in the east ²⁷27. Gatti LV, Basso LS, Miller JB, Gloor M, Gatti Domingues L, Cassol HLG, et al. Amazonia as a carbon source linked to deforestation and climate change. Nature 2021; 595:388-93.. Combined to that, there is the advance of deforestation and increasing forest degradation toward the interior of the forest, exposing the population to new vectors of diseases such as mosquitoes and other types of viruses, in addition to jointly providing a more favorable environment for the occurrence of fires.

In 2023, we will face El Niño, which causes droughts and/or increased temperature in some regions of the Amazon, and data indicate that it should be of greater intensity than the historical average, developing over the coming months. We already know of the high rates of deforestation in recent years, indicating that these areas will burn, and could turn into large fires. We observe the challenges of the current government in keeping the promise of resuming the environmental agenda, still with limited success and established regressions. At the same time, the Amazon Summit assembly is planned for August this year in Belém (Pará State) and there is confirmation of the United Nations Climate Change Conferences (COP 30), which will also be held in Belém in 2025 - amid discussions on oil drilling at the Amazon river mouth with support from all the region’s governors. In this political seesaw, in which a fragmented vision predominates, separating environmental issues from economic and social issues, the Brazilian State continues without integrated short- and long-term plans to enable sustainable, socially and environmentally fair development for the Amazon and for Brazil with clear indicators and goals and guaranteed resources, subject to monitoring by society.

Acknowledgments

L. O. Anderson thanks the Voices of Recovery project team, supported by TransAtlantic Platform (http://www.transatlanticplatform.com/): International Development Research Centre (IDRC; Canada) (projects 109835-002 and 109835-003); Colombian Ministry of Science, Technology and Innovation (MINCIENCIAS) and Francisco José de Caldas Fund (Colombia) (project 80740-094-2022); São Paulo State Research Foundation (FAPESP) (project 2021/07660-2); and the UK Arts and Humanities Research Council (AHRC) (project AH/X001733/1). The opinions expressed in this material are the responsibility of the authors and do not necessarily reflect the views of the funding agencies.

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