Cited by 122Air Quality and Health ImpactsClimate Change and Health ImpactsFire effects on ecosystems

The DOI matches its Crossref record; 38 of the 38 references it cites were found in a registry or an index; 21 of the 24 sources its claims cite were checked for support.

Health impacts of wildfire-related air pollution in Brazil: a nationwide study of more than 2 million hospital admissions between 2008 and 2018

Open access
Requia, Weeberb J., Amini, Heresh, Mukherjee, Rajarshi, Gold, Diane R., Schwartz, Joel D.·2021·Nature Communications

Abstract

We quantified the impacts of wildfire-related PM 2.5 on 2 million hospital admissions records due to cardiorespiratory diseases in Brazil between 2008 and 2018. The national analysis shows that wildfire waves are associated with an increase of 23% (95%CI: 12%–33%) in respiratory hospital admissions and an increase of 21% (95%CI: 8%–35%) in circulatory hospital admissions. In the North (where most of the Amazon region is located), we estimate an increase of 38% (95%CI: 30%–47%) in respiratory hospital admissions and 27% (95%CI: 15%–39%) in circulatory hospital admissions. Here we report epidemiological evidence that air pollution emitted by wildfires is significantly associated with a higher risk of cardiorespiratory hospital admissions.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This nationwide Brazilian study found that wildfire-related PM2.5 during wildfire waves was associated with higher cardiorespiratory hospital admissions from 2008 to 2018. The strongest national associations were a 23% increase in respiratory admissions and a 21% increase in circulatory admissions.

Key findings

  • Across Brazil, wildfire waves were associated with a 23% increase in respiratory hospital admissions (95% CI: 12–33%) at a 5-day moving average and a 21% increase in circulatory hospital admissions (95% CI: 8–35%) at a 2-day moving average.
  • In the North region, where most of the Amazon is located, the estimated increases were 38% for respiratory admissions (95% CI: 30–47%) and 27% for circulatory admissions (95% CI: 15–39%).
  • Regional heterogeneity was substantial: the Midwest had a 20% increase in respiratory admissions (95% CI: 13–26%) at 5 days and a 56% increase in circulatory admissions (95% CI: 36–76%) at 2 days.
  • The study included 2,044,038 cardiorespiratory hospital admissions; 50.2% were respiratory and 49.8% circulatory.

Methods

  • Time-stratified case-crossover design using conditional logistic regression, comparing exposure on hospital admission days with control days matched by day of week, month, and calendar year.
  • Data covered 2,044,038 hospital admissions for respiratory (ICD-10 J00–J99) and circulatory (ICD-10 I00–I99) diseases in Brazil from 2008 to 2018, with wildfire records from INPE and PM2.5, other pollutants, and weather from ECMWF/CAMS ensemble models.
  • “Wildfire wave” was defined as any day when wildfire records and PM2.5 concentration exceeded the 99th percentile of the 2008–2018 regional time series; region-specific odds ratios were meta-analyzed with random effects to estimate national averages.

Limitations

  • The authors state that care-seeking behavior likely led to underestimation of cases, that the fixed annual definition of wildfire waves may cause misclassification, that predicted air pollution and meteorological variables may introduce exposure measurement error, and that hospital admission forms may contain errors.
  • The text also makes evident that some subgroup analyses by region, sex, and age had very large groups of ties and could not be computed because the Survival package algorithm may fail due to overflow.
  • The authors note that regional heterogeneity may reflect cultural, social, behavioral, environmental, and healthcare-access differences, including unequal distribution of health facilities across Brazil.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1038/s41467-021-26822-7

Cites

38 of 38 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Figures

Fig. 1 Spatial distribution of hospital admissions and exposure variables. Nationwide occurrences of respiratory and circulatory hospital admissions (total from 2008 to 2018) (A, B). Concentrations of PM2·5 (mean over the study period) (C) and wildfire density (D) (based on Kernel density with an output cell size of 0.15°; here we accounted for all wildfire records over the study period within a radius of 0.28°) in Brazil.
Fig. 1 Spatial distribution of hospital admissions and exposure variables. Nationwide occurrences of respiratory and circulatory hospital admissions (total from 2008 to 2018) (A, B). Concentrations of PM2·5 (mean over the study period) (C) and wildfire density (D) (based on Kernel density with an output cell size of 0.15°; here we accounted for all wildfire records over the study period within a radius of 0.28°) in Brazil.CC BY · PubMed Central
Fig. 2 Association between hospital admissions and wildfire-related PM2.5. Regional percentage increase in risk (and 95% CI) of hospital admissions (A, respiratory diseases; B, circulatory diseases) associated with wildfire-related PM2.5 in wildfire waves for the moving averages 1–5 days. Note 1: Numbers in x-axis indicate the moving averages. Note 2: “x” means that there were very large groups of ties, which a large number of health events (defined as case day) is out of a large number of subjects (case plus control days). The algorithm in the Survival package may refuse to undertake the task (the computation is infeasible) due to overflow for the subscripts. Note 3: Red (Midwest), blue (North East), orange (North), green (South East), and purple (South). Note 4: n = 2,044,038 individuals.
Fig. 2 Association between hospital admissions and wildfire-related PM2.5. Regional percentage increase in risk (and 95% CI) of hospital admissions (A, respiratory diseases; B, circulatory diseases) associated with wildfire-related PM2.5 in wildfire waves for the moving averages 1–5 days. Note 1: Numbers in x-axis indicate the moving averages. Note 2: “x” means that there were very large groups of ties, which a large number of health events (defined as case day) is out of a large number of subjects (case plus control days). The algorithm in the Survival package may refuse to undertake the task (the computation is infeasible) due to overflow for the subscripts. Note 3: Red (Midwest), blue (North East), orange (North), green (South East), and purple (South). Note 4: n = 2,044,038 individuals.CC BY · PubMed Central
Fig. 3 Regional percentage increase in risk (and 95% CI) of hospital admissions associated with wildfire-related PM2.5 in wildfire waves for the moving averages 1–5 days by sex and age. Note 1: x-axis indicates the moving averages. Note 2: “x” means that there were very large groups of ties, which (a large number of health events (defined as case day) is out of a large number of subjects (case plus control days). The algorithm in the Survival package may refuse to undertake the task (the computation is infeasible) due to overflow for the subscripts. Note 3: Red (Female), blue (Male), orange (0–5 years), green (35–64 years), and purple (>64 years). Norte 4: Left panels (respiratory hospital admissions), right panels (circulatory hospital admissions), panels on the first row (Midwest), panels on the second row (North East), panels on the third row (North), panels on the fourth row (South East), and panels on the last row (South).). Note 5: n = 2,044,038 individuals.
Fig. 3 Regional percentage increase in risk (and 95% CI) of hospital admissions associated with wildfire-related PM2.5 in wildfire waves for the moving averages 1–5 days by sex and age. Note 1: x-axis indicates the moving averages. Note 2: “x” means that there were very large groups of ties, which (a large number of health events (defined as case day) is out of a large number of subjects (case plus control days). The algorithm in the Survival package may refuse to undertake the task (the computation is infeasible) due to overflow for the subscripts. Note 3: Red (Female), blue (Male), orange (0–5 years), green (35–64 years), and purple (>64 years). Norte 4: Left panels (respiratory hospital admissions), right panels (circulatory hospital admissions), panels on the first row (Midwest), panels on the second row (North East), panels on the third row (North), panels on the fourth row (South East), and panels on the last row (South).). Note 5: n = 2,044,038 individuals.CC BY · PubMed Central

Verification

Claims the paper makes

22 Own result · 14 Own method · 9 Partly supported · 5 Supported · 2 No full text of the sources · 2 Own interpretation · 2 No basis given · 1 Supported so far · accuracy not yet measured

Show all 32 claims

  • Probably not a substantial claim. 15
  • It may state two separate claims as one. 12
25 of 25
  • The paper relies on this without support.

    Fine particulate matter (PM2.5) is the major pollutant emitted by wildfires.

    “Fine particulate matter (PM2.5) is the major pollutant emitted by wildfires.”
  • The paper relies on this without support.

    Brazil is a very fire-prone region.

    “Given that Brazil is very fire-prone region”
  • The paper relies on this without support.

    Different types of biomass in Brazil are strongly correlated with wildfire events over space and time.

    “where there are different types of biomass (Amazon Forest, Cerrado, Atlantic Forest, Caatinga, Pampa, and Pantanal) that are strongly correlated with wildfire events over space and time”
  • The paper relies on this without support.

    There is a critical challenge related to land use in Brazil that correlates to wildfire occurrence.

    “where there is a critical challenge related to land use (e.g., agriculture, deforestation etc.), which also correlates to wildfire occurrence”
  • The paper relies on this without support.

    The distribution of health facilities varies drastically by region in Brazil, with more per capita in the South than in the Amazon region, including the North.

    “In Brazil, the distribution of health facilities varies drastically by region. For example, there are many more health facilities per capita in the South than in the Amazon region, including the North.”
  • The paper relies on this without support.

    People with cardiorespiratory symptoms during wildfire episodes may not seek medical care, leading to underascertainment of hospital admissions.

    “given the presence of the individual perceptions and decisions to seek medical care after symptoms of cardiorespiratory diseases during wildfire episodes (as mentioned above), there will be different types of persons.”
6 of 6

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

1 of 1

Citations

Cites

Research works printed but not linked: 2

  1. Ignotti, E. et al. Impact on human health of particulate matter emitted from burnings in the Brazilian Amazon region. Rev. Saude Publica 44, 121–130 (2010a). · DOI · Paper page
  2. Reid, C. E. et al. Critical review of health impacts of wildfire smoke exposure. Environ. Health Perspect. 124, 1334–1343, https://doi.org/10.1289/ehp.1409277 (2016a). · DOI · Paper page

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Metadata

Authors
Requia, W. J., Amini, H., Mukherjee, R., Gold, D. R., & Schwartz, J. D.
Affiliations
  • University of Copenhagen (DK)
  • Harvard University (US)
  • Brigham and Women's Hospital (US)
Venue
Nature Communications
Published
2021-11-12
Volume
12
Issue
1
Pages
6555-6555
ISSN
2041-1723 (ISSN-L)
OpenAlex
W3213522055
Cited by
122
References
37
Citations by year
2026: 30 · 2025: 30 · 2024: 23 · 2023: 23 · 2022: 16
FWCI
6.14
Type
journal article
Language
en
Open access
Locations
  • Nature Communications (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Research at the University of Copenhagen (University of Copenhagen) (publishedVersion, cc-by)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
Ministry of Science, Technology and Innovation | Conselho Nacional de Desenvolvimento Científico e Tecnológico
Topics
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Air Quality and Health Impacts
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Climate Change and Health Impacts
  • Physical Sciences › Environmental Science › Global and Planetary Change › Fire effects on ecosystems
Keywords
wildfire smoke, air pollution health effects, respiratory hospital admissions, Amazon wildfires, Northern Brazil, particulate matter exposure
MeSH terms
Air Pollutants, Air Pollution, Brazil, Hospitalization, Humans

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