Artigos

INTRODUCTION
Air quality is closely linked to both local and global ecosystems, being mainly influenced by factors such as consumption habits, level of pollutant concentration emitted by different sources, meteorology and the geography of each region. The use of fossil fuels, especially in motor vehicles, and industrial activity are significant sources of atmospheric contamination worldwide, contributing to increased emissions of particulate matter (PM), carbon monoxide (CO), volatile organic compounds (VOCs), nitrogen oxides (NOx), and sulfur oxides (SOx). Additionally, forest fires represent a significant global concern due to the emission of fine particulate matter (PM2.5) and their adverse effects on human health.1
In addition to the evident climatic impact caused by these changes in the concentration of greenhouse gases and pollutants, numerous studies have been conducted to assess possible repercussions on human health, revealing an increase in negative outcomes such as premature deaths and high morbidity due to cardiovascular diseases. Chronic exposure to inhaled pollutants is also associated with a higher incidence of asthma, chronic obstructive pulmonary disease (COPD), lung cancer, reduced lung function, and developmental lung anomalies in children, who, along with the elderly, constitute the population most vulnerable to air pollution exposure.2
In light of this, various initiatives have been advised by the World Health Organization (WHO)3 to reduce the emission of atmospheric pollutants, such as the implementation of milestones and safe levels for particulate matter. However, these efforts have yielded unsatisfactory results. In Brazil, environmental pollutants are typically quantified by monitoring stations of environmental agencies, but not all states have such control agencies, which sets a precedent for increased pollution.4 Nonetheless, even when adhering to the air pollutant limits outlined in WHO's Global Air Quality Guidelines,5 respiratory health issues persist at alarming rates.
Assessing the health impacts requires careful consideration of population-specific and location-specific factors, particularly regarding atmospheric pollution. Comprehensive understanding and measurement of these factors are crucial for developing effective public policies. Therefore, this study aims to evaluate the detrimental effects of atmospheric pollution on public health in Brazil through an integrative review.
METHODS
Conducted in June 2024, this integrative literature review, which followed a modified six-step framework proposed by de Souza et al.,6 aimed to analyze articles related to the main atmospheric pollutants and their impacts on public health in Brazil. The objective was to address the guiding research question: "What is the impact of atmospheric pollution on the collective health of the Brazilian population?". The inclusion criteria comprised articles that analyzed atmospheric pollution and its health impacts within Brazil, with full texts available in English and/or Portuguese, published between 2013 and 2024, and freely accessible. Conversely, the exclusion criteria consisted of studies that did not analyze Brazilian regions, articles published before 2013, and those in languages other than English or Portuguese.
The databases utilized included the Latin American and Caribbean Health Sciences Literature (LILACS), Scientific Electronic Library Online (SciELO), and PubMed/Medline, aligned with the Biblioteca Virtual em Saúde (BVS). The search strategy employed descriptors and Boolean operators: “Air Pollution” AND (Health OR “Public Health”) AND Brazil AND “Adverse Effects,” as established by the Descritores em Ciências da Saúde (DeCS) and Medical Subject Headings (MeSH). Duplicate removal, data extraction from each included study, and reference management were facilitated using the online software Rayyan.7
RESULTS AND DISCUSSION
This approach identified 193 articles meeting the specified research criteria. After removing duplicates and reviewing titles/abstracts, 68 articles were initially selected for full-text review. Of these, 51 studies did not present outcomes of interest. Subsequently, 17 publications were identified as relevant for inclusion in the study. Additionally, two articles were manually included to enrich the discussion, bringing the total number of articles reviewed to 19 (figure 1).
Studies have revealed variations in the territorial scope of research due to the extensive geographic magnitude of the federative units of Brazil and the distinct characteristics of its territories, such as population organization, climatic differences, and the diverse productive activities conducted. Despite the heterogeneity of climatic conditions, this diversity has, in fact, aided in precisely delineating the impacts that pollutants can have.
The most extensively analyzed region was São Paulo, with more than five studies focusing primarily on this state. The majority of the studies were available in both English and Portuguese, totaling ten studies. Only a few studies were exclusively available in English, amounting to three, while six studies were available solely in Portuguese. Most of the articles, totaling ten, were published before 2020, while nine were published after this year (table 1).
Air pollutants and their impact
Air pollution, stemming from substances such as suspended particles (PM10 and PM2.5), SO2, NO2, O3, has been linked to various negative health effects in the population. The incidence of respiratory diseases emerged as the most significant indicator for analyzing the effects of air pollution on health. Respiratory diseases have notably emerged as a key indicator of the health impacts of air pollution. Evidence shows a significant correlation, with a 1.4% increase in total hospitalizations and admissions of children under 5 years old for respiratory diseases per 10 ?g/m³ increase in PM10 levels.8,9 Moreover, both short-term and long-term exposure to PM2.5 has been associated with mortality from cardiovascular and respiratory diseases, as well as various types of cancer.10 Regarding exposure duration, it is important to emphasize that acute respiratory effects are linked to recent exposure, typically lasting hours or days, whereas chronic respiratory effects are associated with prolonged exposure, generally exceeding six months.2
Research into the toxicity mechanisms of PM2.5 suggests that it contributes to mortality through various pathways, including inflammation, pulmonary oxidative stress, and DNA damage. Due to their inhalable nature and small size of up to 2.5 ?m in diameter, PM2.5 particles can migrate from the interstitial spaces to other organs, potentially increasing the risk of developing lung cancer and other malignancies.10 In addition to PM2.5, pollutants such as PM10, NO2, SO2, and O3 are associated with increased adverse respiratory events and are believed to operate through mechanisms similar to those of PM2.5 toxicity, although these mechanisms are less well elucidated. Particulate matter appears to exert its effects through inflammatory mediators and oxidative stress, with responses varying according to the species present in the particle composition, which may include metals, organic carbon, ions (sulfates and nitrates), and other compounds.11
Other gasses, such as carbon monoxide (CO), have demonstrated an eightfold increase in total hospitalizations with a 1 ppm rise in their levels, while sulfur dioxide (SO2) showed a 2.6-fold increase with an additional 10 ?g/m³.12 Consequently, it can be asserted that air pollution, specifically PM10, and its effects on respiratory diseases impose high costs on public health services, leading to significant and avoidable additional expenses in Brazil, estimated at approximately 1.7 billion dollars annually.13
In addition to the economic impact related to healthcare costs, diminished productivity, activity limitations, and premature deaths, it is estimated that air pollution results in over 20,000 deaths annually in Brazilian metropolitan regions. The financial burden of these preventable losses is expected to motivate the implementation of measures to reduce pollutant emissions.14
There is a significant correlation between these pollutants and the increase in emergency visits for respiratory diseases in children aged 0 to 6 years.15 It is essential to note that one study15 recorded an increase in emergency visits from March to June, a timeframe that coincides with autumn and the start of winter. During such seasonal periods, factors such as lower temperatures, higher pollutant concentrations due to temperature inversion, and reduced rainfall exacerbate respiratory infections.15
Air pollution from vehicular emissions
In the 1950s, motor vehicles have been identified as the predominant contributors to pollution in urban areas. As a response, in 1986, stringent emission controls for motor vehicles were established, aiming to reduce emissions and promote sustainable technologies. According to the WHO, elevated levels of air pollution are frequently a byproduct of unsustainable policies in sectors such as transportation. Therefore, investing in improvements in this sector could result in substantial healthcare savings.14
According to the Environmental Company of the State of São Paulo (CETESB), PM10 assessments in São Paulo were conducted at 58 stations, including 22 in the Metropolitan Region of São Paulo (MRSP) and 36 in inland and coastal areas. In 2023, the average PM10 concentration in the MRSP was 27 µg/m³, with 137 days of high concentration recorded across the state, particularly at the Cubatão–Vila Parisi station, situated in an industrial area. These elevated levels occurred primarily during the winter, due to atmospheric stability.16
PM2.5 measurements were carried out at 40 stations, with 27 in the MRSP and 13 in inland/coastal regions. In the MRSP, 10 out of the 16 stations with annual data exceeded the daily limit of 50 µg/m³, while none of the 13 inland stations surpassed this standard. This indicates a higher prevalence of fine particulate matter in the MRSP, in contrast to coarser particles, which are more predominant in PM10. Regarding the annual limit of 17 µg/m³, only two MRSP stations, located near traffic corridors, reported values above the permitted threshold.16
The tracking of smoke, conducted at six-day intervals, represents a critical indicator for characterizing combustion processes and assessing air pollution levels. In 2023,16 no monitoring stations within the MRSP or in the state’s interior reported concentrations exceeding the established annual (35 µg/m³) or daily (100 µg/m³) thresholds. Total Suspended Particles (TSP), which include particles with aerodynamic diameters up to 50 µm, are utilized to evaluate particulate matter deposition in specific regions. TSP analyses were performed at seven stations, yielding representative data for all locations. Within the MRSP, neither the annual nor daily regulatory limits were breached. However, at the Cubatão–Vila Parisi station, exceedances of the daily (240 µg/m³) and annual (80 µg/m³) standards were recorded, indicating localized challenges in maintaining air quality standards.16
Studies conducted in Brazil, particularly in São Paulo, have associated atmospheric pollution from vehicular emissions with a rise in respiratory diseases and other health issues.8,17-19 A significant correlation has been found between elevated PM10 emissions and increased hospitalizations for heart failure, with higher morbidity rates observed in cities with dense vehicular traffic.17 In the state of São Paulo, it is projected that approximately 250,000 deaths will be attributable to pollution by 2030 if PM2.5 levels remain consistent with those in 2011.18
Similarly, individuals residing near high-traffic roads are more susceptible to mortality from heart diseases. It is important to consider that high-traffic areas generally have lower real estate market values, which may lead to their occupation by lower-income populations.20 Individuals with lower income also face greater difficulties in accessing healthcare services, which can introduce a confounding factor in research. Conversely, in the municipality of São Paulo, higher socioeconomic status was found to be associated with living in high-traffic areas, which correlates with an increased risk of hospitalization for respiratory system cancers.19
In light of this socioeconomic disparity, various studies advocate for public policies that advance infrastructure development, better public transportation, clean technology usage, and sustainable development.12,14,15,17-19 Such measures would lead to better air quality in regions housing vulnerable populations, thereby enhancing public health and reducing the incidence of various diseases.
Exposure to pollutants from occupational activities
Occupational activities can result in work-related intoxication due to daily exposure to pollutants. In a study conducted in Mato Grosso,21 identified pesticides and industrial dust as the main sources of exposure, predominantly affecting males, older age groups, and individuals with lower educational levels.21 Considering these findings, it is essential to account for the complex variables in the illness process, including production methods, air circulation in poorly ventilated indoor spaces, and pollutant exposure patterns across different populations.
It is important to note that workers often do not perceive the pollution conditions to which they are subjected. In Moniz's study,22 it was found that the daily burning of small amounts of biomass by the ceramic industry in Itaboraí (RJ) significantly contributes to poor air quality due to the dispersion of dust, clay, and other particulates.
However, the smoke from the kilns was not perceived by the workers and the local population as a health risk. It is believed that the acceptance of these conditions is a form of collective defense mechanism among communities exposed to industrial hazards, given their inability to effectively change the situation over time.22
Within the context of agricultural worker health, it is emphasized that the current large-scale monoculture production model fosters reliance on chemical products23 and promotes the practice of agricultural burnings to increase profits.13 Family farms attempting to abstain from the usage of pesticides often face suppression within this prevailing production paradigm.23 Intoxications are most frequently reported during harvesting, spraying, and seed treatment phases,23 although underreporting is presumed due to the pressures workers face to keep information undisclosed.
Atmospheric pollution from agricultural burning
Another relevant point in the discussion on this topic is the impact of agricultural burnings on atmospheric pollution, with consequences for air quality and human health. The practice of burning sugarcane crops, conducted to facilitate harvesting and increase profits, is widespread and constitutes a significant source of particulate matter dispersion in the air, especially PM2.5.13 Additionally, in Brazil, the deforestation of the Amazon rainforest and the biomes of the Midwest region contribute to increasingly severe wildfires, which, propelled by air currents, have the potential to disperse pollutant particles at a continental level, leading to numerous effects on human health.23
From this perspective, despite burnings being a common practice strongly linked to the economy, it is crucial to explore more sustainable alternatives that pose fewer health risks, such as green harvesting. This approach aims to prevent the development of respiratory diseases and consequently reduce public health expenditures. According to Gao et al. (2024),1 their study was the first to establish an association between PM2.5 levels from burnings and cardiovascular deaths, ischemic heart disease, and stroke, resulting in a total of 35,847 cardiovascular deaths attributed to PM2.5 over an eight-year period (2010-2018). These alarming numbers underscore the necessity for governmental actions to mitigate mortality and expenditures associated with cardiovascular diseases caused by air pollution, as well as the need for further studies to validate this connection.
Limitations
Atmospheric pollution and its effects on human health encompass a vast and intricate topic requiring numerous considerations and in-depth analyses. However, there is a considerable deficit in research exploring the impacts of pollutants on systems other than the respiratory and cardiovascular. Additionally, there is a notable scarcity of information on various atmospheric pollutants, which can compromise or hinder the interpretation of available evidence. More than half of the studies also face data quality issues, such as the absence of monitoring stations in certain locations, data loss due to instrument failures, lack of data on hospital admissions in non-SUS hospitals, seasonal variability affecting values, and the absence of data that should be available in the database during collection. These challenges present substantial obstacles to the meticulous analysis of statistics.1,8,9,11,12,15,17-20 In this context, conducting further research on this topic is essential to fill existing gaps and provide a more comprehensive and complete understanding of this crucial issue.
CONCLUSION
The findings were primarily derived from studies focused on the context of the metropolitan region of São Paulo. Moreover, a significant correlation was identified between the increase in respiratory disease cases and the emission of atmospheric pollutants, with an emphasis on fine particulate matter (PM10 and PM2.5). Given the documented harmful effects, it is essential to leverage these data towards the development of specific public policies targeting the reduction of pollutant emissions.
The assessment of both short- and long-term effects of air pollution on public health is a continually evolving research area, with new studies expected to be published in the coming months and years. Our review of existing studies examined the evidence and identified the statistical challenges researchers face when analyzing the link between air pollution and respiratory comorbidities. We recommend that future research further explores these challenges and expands on current findings to provide a deeper understanding of the impact of air pollution on public health.
REFERENCES
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AUTHORS' CONTRIBUTION
Each author has made substantial contributions to the study, adhering to the specific roles delineated by the CRediT (Contributor Roles Taxonomy) guidelines.
Virgilio Astori: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Visualization, Writing - original draft, Writing - review & editing; Wdmila Maria Uliana: Data curation, Formal analysis, Supervision, Writing - original draft, Writing - review & editing; Bruna Veríssimo Lopes: Data curation, Formal analysis, Supervision, Writing - original draft, Writing - review & editing; Letícia Pontes de Oliveira: Conceptualization, Resources, Visualization, Writing - original draft, Writing - review & editing; Fellipe Pesente: Investigation, Writing - original draft, Writing - review & editing; Lucas Rocha Dalto: Investigation, Writing - original draft; Luciene Lage da Motta: Supervision.
CONFLICT OF INTEREST
The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper.
RESEARCH DATA AVAILABILITY
The entire dataset supporting the results of this study was published in the article itself.