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Article

Occupational and Environmental BTEX Exposure: A Bibliometric Analysis Using Scientific Mapping

by
Ahmet Gökcan
1,*,
Hacer Handan Demir
1,*,
Mükerrem Ozdemir
1,
Hüdanur Yasa
1,
Hakan Çelikten
2 and
Göksel Demir
1
1
Department of Occupational Health and Safety, Hamidiye Faculty of Health Sciences, University of Health Sciences, Istanbul 34668, Türkiye
2
Department of Civil Engineering, Faculty of Engineering and Architecture, Kafkas University, Kars 36100, Türkiye
*
Authors to whom correspondence should be addressed.
Atmosphere 2025, 16(12), 1353; https://doi.org/10.3390/atmos16121353 (registering DOI)
Submission received: 8 November 2025 / Revised: 27 November 2025 / Accepted: 28 November 2025 / Published: 29 November 2025
(This article belongs to the Special Issue Environmental Odour (2nd Edition))
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Abstract

BTEX compounds (benzene, toluene, ethylbenzene, and xylene isomers) are aromatic hydrocarbons widely used in various industries. Due to their volatility, they become persistent pollutants in workplace air, posing serious risks to worker health. The aim of this study is to systematically map academic publications on BTEX exposure and health effects and to evaluate the impact of exposure levels in industrial settings on worker health. Publications obtained from the Web of Science database between 2010 and 2025 were bibliometrically analyzed in terms of productivity, collaboration networks, thematic trends, and analysis methods. In addition, the sources of BTEX compound dispersion, analysis methods, and industrial hazard classifications were evaluated through content analysis. According to the findings, Iran and China stood out as the most active countries, with publication intensity peaking in 2023. BTEX exposure was observed to be particularly high in the petrochemical sector. However, there is a lack of studies that systematically address the direct effects on worker health. This study aims to contribute to the more effective management of BTEX-related exposure risks by providing decision-makers with scientifically based and interpretable analyses.

1. Introduction

Volatile organic compounds (VOCs) are of significant environmental concern due to their high vapor pressures and chemical reactivity. These compounds are the focus of intensive research in the fields of atmospheric chemistry, toxicology, occupational health and public health [1]. These compounds may also contribute to global warming, the thinning of the stratospheric ozone layer, and the formation of tropospheric ozone [2]. VOCs, including BTEX, are emitted into the atmosphere from a variety of sources, including biogenic, anthropogenic, and natural origins. Additionally, these compounds can also form in the air as degradation products of other VOCs [3]. BTEX compounds (benzene, toluene, ethylbenzene, and m,p,o-xylene) are a significant class of VOCs and the focus of numerous toxicological studies. These compounds are a source of pollution in urban environments, originating from vehicle exhaust [4]. These compounds are frequently measured, particularly to assess traffic-related air pollution [5]. These pollutants pose a significant health risk, especially in megacities characterized by heavy traffic.
BTEX compounds are volatile organic compounds that are widely used in many industrial processes, primarily in the energy and chemical sectors. They are released into the environment from pyrogenic, petrogenic, and chemical sources [6]. BTEX compounds are regarded as a critical subgroup from both an environmental and health perspective due to their monochromatic structures and toxic effects [7,8]. Due to their toxic structures and widespread distribution, they have become an important research topic in the fields of public health, the environment, and occupational health and safety [9].
From an occupational health and safety (OHS) perspective, BTEX components are among the chemical substances that require careful evaluation, particularly in work environments characterized by intensive industrial activities [10]. They can cause acute poisoning and, due to their carcinogenic effects, can damage the central nervous system, lymphatic system, circulatory system, and reproductive organs [11,12]. BTEXs are characterized by their lipophilic properties, small particle size and absence of ionic charge, which facilitate absorption by biological membranes such as alveoli, cell walls and skin [13]. Exposure to BTEX has adverse effects on the liver, nervous system, heart, and kidneys, and increases the risk of developing non-lymphocytic leukemia [6]. Benzene has been classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC), while ethylbenzene has been classified as a Group 2B carcinogen [10,14]. Furthermore, all BTEX components pose significant risks to human health that extend beyond the potential for carcinogenesis [15,16].
Consequently, the assessment and limitation of BTEX exposure is important. The occupational exposure limit values established by international authorities for this purpose serve as a fundamental reference for controlling workers’ exposure to toxic chemicals (see Table 1) [10,17]. In the context of occupational health and safety, it has become imperative to regulate workers’ exposure to toxic chemicals by adhering to the limit values stipulated in the workplace.
A substantial increase has been observed in the number of scientific publications concerning BTEX exposure in recent years. This increase signifies that BTEX has emerged as a priority research topic on the international stage within the domains of occupational health and safety, environmental sciences, and public health. However, a comprehensive bibliometric study is lacking in literature, as such studies systematically examine research trends in this field and reveal thematic developments and collaboration networks.
The objective of this study is to analyze scientific publications related to BTEX exposure using bibliometric methods to reveal the evolution of knowledge in the field, research gaps, and interdisciplinary collaboration dynamics.

2. Materials and Methods

2.1. Bibliometric Analysis

The rapid increase in the number of academic publications today makes it difficult for researchers to keep up with new studies; this situation causes experimental studies to become fragmented and voluminous, making it difficult to systematically evaluate previous research [18]. In this context, literature reviews are of critical importance in synthesizing existing knowledge to develop research lines, maintain professional expertise, and provide evidence-based insights [19]. Researchers utilize various qualitative and quantitative literature analysis methods to interpret and organize previous studies. Among these methods, bibliometric analysis provides a systematic, transparent, and repeatable approach to examining the transformation of the intellectual, social, and conceptual structure of a particular research field over time by evaluating scientific outputs using statistical data [20,21,22].
Bibliometric analysis is a quantitative research method, and various software tools are utilized to perform these analyses [23]. One of these tools is the Bibliometrix R package (Version 5.2.0), which offers comprehensive quantitative analysis capabilities for bibliometric and scientific measurement studies. This package has been developed on the open-source R programming language. It provides significant advantages that make R stand out from other alternatives in scientific computing. These advantages are a result of the package’s powerful statistical algorithms, high-quality numerical routines and integrated data visualization tools [19,24,25]. In addition to the capacity for comprehensive data storage, its ability to visualize data in various graph types sets it apart from similar libraries. These features enable researchers to conduct comprehensive and visually rich analyses on data sets [26]. Access to this visual interface is provided via the R-based Bibliometrix package using the “bibliometrix::biblioshiny()” command, thereby enabling bibliometric analyses to be performed in a user-friendly manner [19,27].

2.2. Data Sources

The objective of this study is to evaluate scientific trends and research dynamics from an occupational health and safety perspective. To this end, the development of the literature on occupational and environmental BTEX exposure over time will be analysed using bibliometric methods.
In this context, data related to the specified research topic was obtained entirely from the Web of Science (WoS) Core Collection database. WoS stands out as one of the most widely used and highest impact academic databases in the scientific field [28,29]. This search strategy is a widely utilized technique within the domain of bibliometric analysis and is regarded as a methodologically sound approach [30].
The data collection process was systematically conducted using the WoS database. The following Boolean query was applied using the advanced search engine: TS = (“BTEX” OR “BTEX exposure”) AND TS = (“occupational health risk” OR “environmental risk” OR “health impact”). The keywords in question were queried under the “All Fields” filter, and all relevant fields were scanned. During the scanning process, the following exclusion criteria were applied: review articles, proceeding papers, corrections, early access and book chapters. Review articles, conference proceedings, and similar publications were excluded, as they do not present new findings and may contain repetitive content. This approach ensures that the methodology relies on primary research findings and that comparable data sets are used. Only studies published between January 2010 and September 2025 were considered.

2.3. Research Questions

In the design of bibliometric studies, answers are sought to a series of research questions structured in line with the defined scientific scope. The present study utilized a comprehensive bibliometric and content-based analytical framework to examine the relationship between exposure to BTEX compounds (benzene, toluene, ethylbenzene, and xylene) and occupational health and safety.
The analysis focused on the following research questions:
  • What is the annual number of publications on the subject?
  • What is the impact of sources (journals) related to the subject?
  • What is the distribution of scientific publications on the subject by country, institution, and author?
  • What is the citation status of authors and countries?
  • What are the relationships between academic institutions, authors, and keywords?
  • What is the density of prominent keywords?
  • What are the collaboration networks of influential authors, institutions, and countries?
  • How have thematic concepts developed and diversified?
  • What are the conceptual structure maps of co-occurring keywords?
  • What industrial and environmental sources cause BTEX exposure?
  • What are the most commonly used analysis methods for assessing BTEX exposure?
  • What are the biological monitoring methods for BTEX exposure?
The analytical framework of the study is presented in Figure 1.
All analyses were conducted through the systematic processing of bibliometric data and the listing of significant studies; thus, trends in the literature, thematic concentrations, and collaboration networks were comprehensively revealed.

3. Results and Discussion

The principal findings pertaining to the research data are set out in Table 2. A total of 269 research articles obtained from 88 different sources were examined within the scope of the study. The mean citation rate of 23.97 indicates that the relevant publications have exerted a substantial influence on the existing body of literature. The analysis was made by the contributions of 1.339 researchers. The presence of international co-authorship in 29.74% of the publications indicates that the research field attracts global interest and that international collaboration networks are robust.

3.1. Number of Scientific Articles Published Annually

As can be seen in Figure 2, there has been a marked upward trend in the number of scientific articles evaluating BTEX exposure between 2010 and 2025. During this period, there has been a significant shift in the publication landscape, characterized by substantial changes in both the quantity and the temporal distribution of publications. It is evident that the acceleration which commenced in 2016 signifies an augmentation in academic interest and a progression towards more systematic research activities.
When examining publication dynamics:
  • 2010–2015: The annual average output is approximately five articles, with a low and fluctuating output.
  • In the period 2016–2022, there was a rapid increase in the number of articles published, accompanied by a significant thematic diversification. On average, approximately 27 articles were published annually.
  • 2023–2025: It is evident that there has been a relative stabilization, as evidenced by the publication numbers, which have now stabilized within the 22–23 range.
This trend indicates that knowledge production in literature has undergone not only a quantitative but also a structural transformation. These findings, based on time series analysis, provide an important reference point for determining future research strategies and identifying thematic gaps. Despite an increase in the number of studies evaluating BTEX exposure levels in recent years, a significant gap remains in the literature.

3.2. Journals in Which Scientific Studies Are Published

Figure 3 illustrates the journals in which scientific studies on BTEX exposure have been published. This distribution provides significant insights into both thematic priorities and research trends.
With a total of 17 articles, Environmental Science and Pollution Research is the journal with the highest number of publications. The journal provides extensive coverage of studies on topics such as sustainable environmental management and the distribution and effects of environmental pollutants. Atmospheric Pollution Research, ranked second, has 12 articles focusing on atmospheric processes and air pollutants. Environmental Monitoring and Assessment, Environmental Pollution and Science of the Total Environment have the same number of publications and include studies on environmental monitoring, the effects of pollution on human and ecosystem health, and comprehensive environmental analysis. Air Quality, Atmosphere & Health and Chemosphere follow with ten articles each: the former highlights the relationship between air quality and human health, while the latter focuses on technical content in the fields of toxicology and environmental chemistry. Similarly, the International Journal of Environmental Research and Public Health features studies that address environmental risks from a public health perspective. Finally, with nine articles each, the journals Atmospheric Environment and Environmental Research are among the most important sources of publication, covering studies on the environmental effects of atmospheric components and environmental policies.
The main reasons for the prominence of these journals include:
  • The extensive coverage of environmental and health-based dimensions in research,
  • The proliferation of interdisciplinary approaches,
  • The increase in application and analysis-focused research.
This analysis demonstrates that environmental risks are addressed not only from a technical perspective but also from social and managerial dimensions; therefore, thematic diversity must be considered in bibliometric analyses. The pre-eminence of these journals is attributable to two key factors. Firstly, environmental and health-based themes are given prominent consideration in research. Secondly, these themes occupy a central role in interdisciplinary studies. This finding suggests that trends in publication within the field of environmental sciences are becoming increasingly interdisciplinary, and that there is growing pressure in areas such as health, risk, and policy [31].

3.3. Citation Performance and Publication Volume of Academic Studies

As Figure 4 shows, when the citation performance and publication volume of academic studies published between 2010 and 2025 are examined, both quantitative and qualitative changes over time can be observed.
A study published in 2010 achieved a higher impact level than other articles, with an average of 128.50 citations per article. The year 2010 has been more visible and influential in literature due to both the low number of publications and the long citable year period. Other noteworthy years include 2014, which exhibited an average citation of 60.40, and 2013, which demonstrated an average citation of 44.71. Conversely, the average citation counts for 2011 and 2012 remained relatively low at 11.00 and 9.50.
During the 2015–2019 period, average citation values ranged from 24.00 to 44.38, indicating a relatively balanced distribution over these years. However, following 2020, a substantial decrease in citation numbers was evident, particularly from 2022 onwards. While the average citation count was 11.61 in 2022, this value declined to 11.61 in 2024 and 0.87 in 2025. This decline can be explained by two factors. Firstly, the publications have not yet been cited for a sufficient period. Secondly, there has been an increase in competition in literature.
When examining the mean citations per year variable, the highest values were obtained in 2018 (5.55) and 2019 (5.57). However, these rates have declined since 2022 and have fallen to 23.00 as of 2025. This situation indicates that new publications have not yet gained sufficient visibility and that the citation window has narrowed.
The number of publications (N) has exhibited an upward trend over the years. The number of publications increased from a mere four in 2010 to 41 in 2023, with 22 and 23 publications recorded in 2024 and 2025, respectively. This increase indicates that academic productivity in the field has intensified over time. However, when the increase in the number of publications is evaluated alongside the decrease in the number of citations, it becomes evident that quantitative growth does not necessarily equate to qualitative impact.
Furthermore, an analysis of the ‘citable years’ variable indicates that earlier studies can be cited over a more extensive time. For instance, while this value was recorded as 16 for the year 2010, it was documented as 1 for the year 2025. This phenomenon can be interpreted as indicative of a natural narrowing of the citation window for publications as the years progress, with new studies not yet having been evaluated over a sufficient time.

3.4. Text Mining with Word Clouds and Word Trees

Word clouds and word trees are two text mining methods which reveal thematic densities by visually presenting the most frequently used terms in a text or publication set [32].
As Figure 5 illustrates, the most prevalent keyword in the reviewed literature is “volatile organic compounds (VOC).” This concept forms the core research axis in studies of both environmental and occupational exposure contexts and occupies a central position in existing literature. VOCs are followed by terms such as BTEX, ambient air, benzene, exposure, and emissions. The terms under discussion reflect the importance of topics such as air pollution, sources of pollutants, and health risks in the relevant literature.
Treemap visualization (a) provides a visual representation of the frequency of keywords in literature and their relationships with each other [33]. Larger rectangular areas are indicative of greater frequency of utilization, while smaller areas suggest a comparatively restricted thematic scope. In this context, the prevalence of terms such as VOC and BTEX in the literature indicates that these concepts are the focus of research in the context of air pollution, exposure, and health risks. The pre-eminence of these two terms is primarily attributable to the fact that compounds such as benzene, toluene, ethylbenzene, and xylene isomers (BTEX) are volatile organic air pollutants, originating from both natural and anthropogenic sources [34].
Word cloud analysis (b) similarly provides a visual summary of the most frequently used key concepts in literature. While the term “volatile organic compounds” is the most prevalent, terms such as exposure, ambient air, benzene, occupational exposure, and health-risk assessment are also used extensively in the studies.
When both analyses are evaluated in tandem, it is evident that VOCs are at the core of the existing literature in the context of environmental and occupational exposure. Themes such as health risks, air quality, pollutant sources, and monitoring strategies serve to complement this axis.
This situation supports the interdisciplinary nature of studies in the relevant field and the public health-focused approach. Visual analyses reveal the thematic concentration of compounds such as VOC and BTEX, necessitating a critical assessment of how this dominance shapes research orientations. The increasing presence of BTEX, in particular, is indicative of growing sensitivity to chemical risks. However, this observation also gives rise to questions regarding the representation of other potential contaminants in the existing literature. In this context, visual-based text mining can be regarded as a strategic instrument for identifying not only trends but also gaps in existing literature.

3.5. Thematic Mapping of BTEX Compounds and Their Health Effects

The thematic map in Figure 6 provides a visual representation of the conceptual structure of the literature focusing on BTEX compounds and their health effects by dividing it into four main groups based on density and centrality axes. The map facilitates analysis of inter-thematic relationships and levels of development, as well as strategic evaluation of trends in literature [35,36].
The Motor Themes (High Density & Centrality): The themes in this group have been found to be both methodologically and substantively guiding in the literature. The chemical compounds encompassed within this theme include sulfur compounds, decomposition, tobacco, acetaldehyde, benzene homologs, gas chromatography, pollution characteristics, and particles. These themes are critical in terms of the advanced techniques used in BTEX analyses and the detailed examination of contaminant properties.
Basic Themes (High Centrality, Low Density): These are themes frequently encountered in existing literature and form fundamental reference points. The following terms are to be considered within the scope of this study: indoor air, air pollution, city, water, groundwater, management, volatile organic compounds, ambient air, BTEX emissions, identification, emission, exposure, benzene. These themes form the foundation of research addressing the environmental and health impacts of BTEX.
Niche Themes (High Density, Low Centrality): These represent original and narrow research domains. The following subjects are to be addressed: cancer, industry, drinking water, particulate distribution, surfaces, removal. Despite the paucity of studies addressing these themes, they offer significant potential for in-depth analysis.
Emerging or Declining Themes (Low Intensity & Centrality): The term is employed to denote subjects within the domain of literature that are either losing their relevance or beginning to attract new interest. The following substances and processes are to be considered: pesticides, surface waters, adsorption, models and pollution profiles. The identification of these subjects indicates the potential for further exploration in subsequent research endeavors.
The analysis conducted indicates that the thematic distribution reflects the structure of existing scientific studies and the direction of research trends. Core themes represent areas of BTEX analysis that are methodologically mature and have an established place in the scientific community. Basic themes demonstrate continuity in research into environmental and health impacts. Niche themes represent unique topics that have been studied in a limited number of studies, with the potential for future expansion. Emerging and declining themes show that interest in some topics (e.g., pesticides and surface waters) is declining, while interest in others (e.g., adsorption and pollution profiles) is emerging. This points to a trend of redefining the environmental risks associated with BTEX exposure and of developing new analytical approaches.

3.6. Coupling-Based Clustering Results

The Clustering by Coupling method (a–b), as shown in Figure 7, demonstrates that scientific studies focusing on BTEX and VOCs are concentrated around three primary thematic clusters. These clusters offer a conceptual framework for understanding the field, both in terms of its content and methodological orientations. They encompass interdisciplinary themes such as environmental monitoring, health risks, and analytical methods.

3.6.1. Thematic Cluster Structure and Focus Areas

Blue Cluster: This cluster comprises environmental monitoring studies conducted on ambient air and BTEX parameters. The group’s research is grounded in the domain of environmental engineering, encompassing diverse areas such as air quality assessments, identification of emission sources, and urban exposure analyses.
Red Cluster: Research focusing on health risk assessment and toxicological evaluation is concerned with the effects on human health. This cluster encompasses public health-focused research, including the utilization of biomarkers, the analysis of cancer risk, and the quantitative assessment of toxic exposure. In this context, when evaluated from an occupational health and safety (OHS) perspective, risk analyses related to BTEX and VOC exposure among workers in industrial settings are directly related to this cluster. The occupational hygiene measurements, the determination of exposure limit values, and the effectiveness of personal protective equipment (PPE) constitute the OSH dimension of this thematic structure.
Green Cluster: This text constitutes an overview of studies that have been conducted about analytical methods related to benzene and other VOCs. The methodological diversity of this cluster is reflected in its sampling strategies, laboratory-based analytical techniques, and chemical characterization processes. In this context, workplace environmental measurements and VOC monitoring technologies overlap with the technical tools used in OSH applications.

3.6.2. Centrality and Influence Levels

When evaluated according to their levels of centrality and impact, the terms volatile organic compounds, ambient air, and BTEX constitute the core concepts of the field with both high centrality and high impact values. These concepts represent common research axes where interdisciplinary interaction is concentrated.
Conversely, concepts such as health-risk assessment, benzene, and occupational exposure, despite their lower levels of centrality and impact, reflect unique sub-themes that are critical to OSH practices.
This conceptual clustering analysis shows that scientific studies in the context of BTEX exposure are structured around three main axes:
  • Environmental Monitoring and Air Quality Analysis
  • Assessment of Health Risks and Occupational Safety and Health Practices
  • Analytical Methods and Chemical Characterization
The thematic structure obtained reveals that research into BTEX and VOCs is positioned at the intersection of disciplines such as environmental engineering, toxicology, analytical chemistry, and occupational health. It provides both methodological and application-based transition between these fields. In this context, it is evident that the OSH perspective aligns with the conceptual density observed in the red and green clusters, thereby contributing to its practical application.

3.7. Co-Citation Network Analysis Results

The co-citation network analysis shown in Figure 8 demonstrates that the BTEX and VOC literature is organized around two distinct thematic clusters.
The red cluster comprises preliminary and theoretical studies of fundamental importance, including Hoque (2008), which established the methodological basis of the field in areas such as risk modelling and the definition of exposure parameters.
Conversely, the blue cluster encompasses current and application-oriented studies, including Miri M (2016) and Dehghani M (2018). This cluster represents solution-oriented approaches, such as health risk assessment and field data-based modelling.
The observed intensity of the connection between the two groups indicates that theoretical foundations directly guide current applications. This situation suggests a transition process in the literature from theoretical structure to practical analysis.

3.8. Countries’ Scientific Studies Analysis Results

The map shown in Figure 9 offers a visual representation of the scientific production levels of countries in the relevant research field using color tones.
Dark tones indicate high broadcast frequency, while light tones indicate lower production levels [37].
According to the data set, Iran (n = 426) and China (n = 348) stand out as the countries with the highest number of publications. This finding indicates that these countries are engaged in intensive scientific activity in the relevant research field and make meaningful contributions to scientific work. The United States (n = 78) and India (n = 73), while exhibiting lower frequencies, are among the countries with high impact power on a global scale.
Furthermore, several countries have achieved moderate to low levels of scientific output, including Brazil (n = 39), Thailand (n = 36), South Korea (n = 30), Malaysia (n = 28), Nigeria (n = 27), and Mexico (n = 25). These countries are positioned in the network’s peripheral layers as regional contributors; however, some of them can gain significant visibility due to their strategic locations and thematic focus.
The map visualization reveals that production density shows a distinct clustering, particularly in the Asian continent. Iran and China, as regional leaders, are at the center of scientific production in Asia. This strengthens the role of regional capacity in global scientific interaction. In the Americas, the United States and Brazil are the most prominent countries; in Africa, despite the limited number of publications, Nigeria is positioned as the most active country at the regional level.
The analysis exclusively focuses on countries with the highest number of publications. In addition to the countries listed in Figure 9, there are also publications on BTEX in European countries (e.g., Spain, n = 22; Italy, n = 13; Germany, n = 8; Poland, n = 8; France, n = 5). However, given the comparatively lower number of publications in these countries, they are not listed at the top of the table.
The findings indicate that scientific research in this field is concentrated around certain countries, with Asian countries having increased their publication volume in recent years, thus becoming significant players on a global scale. This situation is indicative of the geographical centralization of scientific production and the integration of regional research capacity into the global knowledge system. In this context, the visual representation of production data facilitates analysis of not only quantitative densities but also the spatial distribution of scientific orientations. The evaluation of the thematic focuses and collaboration networks of the relevant countries will provide a more comprehensive bibliometric framework.

3.9. Three-Field Graph Analysis Results

The Three-Field Plot analysis shown in Figure 10 was developed to provide a visual representation of the structural dynamics of scientific production in the field of environmental sciences. The visual representation, organized in the form of a Sankey diagram, facilitates the concurrent analysis of the relationships established between three pivotal components: authors (AU), thematic keywords (DE), and publication sources (SO). This structure facilitates a comprehensive evaluation of the contributions of individual researchers and the conceptual density of the field, in addition to the academic platforms on which it is published.
Authors such as Shahsavani A, Fazlzadeh M, Kermani M, and Wang Y occupy a central position in the scientific network due to the high number of connections and interaction values they have established with descriptors. Authors in question have produced works on a range of topics, including BTEX, environmental toxicology, air pollution, indoor air quality, and public health. They are regarded as pivotal figures in the conceptual development of the field.
The use of key terms in the form of abbreviations, such as BTEX, volatile organic compounds, air pollution and risk assessment indicates that most of the research has focused on volatile organic compounds, indoor air quality, and the effects of these substances on human health. These themes are of critical importance in terms of assessing environmental risks and developing preventive strategies for public health.
A central position in the examination of published sources is occupied by journals such as Environmental Science and Pollution Research, Science of the Total Environment, and Environmental Research due to both their high impact factors and their hosting of studies on environmental risks. These sources are regarded as the guiding forces in the realm of scientific production, ensuring thematic continuity and academic visibility. In this context, to increase scientific visibility and spread thematic diversity across a wider network of publications, studies should not be limited to high-impact journals but should also be published in different sources.

3.10. Average Citation Count and Normalized Contribution Value Analysis Results

The bibliometric analysis conducted on BTEX exposure is shown in Table 3, evaluating scientific impact not only by the total number of citations but also by the annual average citations and normalized contribution values.
The study by Durmusoglu et al. (2010), which ranks first on the list, has received a total of 319 citations for its assessment of the health risks of BTEX emissions and holds a strong position in terms of thematic centrality with an NTC value of 2.482. The present study evaluated and discussed the health risks associated with BTEX exposure among workers at a solid waste site. The mean concentrations of benzene, toluene, ethylbenzene, and xylene were measured at 140.3, 1271.7, 239.9, and 341.3 μg/m3, respectively. The cancer risk from benzene exposure over a period of 70 years is 67.5 per million, which is below the acceptable limit set by the EPA. Regarding non-carcinogenic risks, the HR values (toluene: 0.015; ethylbenzene: 0.014; xylene: 0.195-ppm) remained below the 1.0 threshold value and were found to be acceptable from a health perspective [2].
Similarly, the study by Dai et al. (2017) examined the VOC characteristics of new residential buildings in Shanghai, deriving an NTC value of 4.834. Recent publications, including Davidson et al. (2021) and Mor & Ravindra (2023), have emerged as key studies in current literature, characterized by high TCperYear and NTC values. In the field of environmental exposure modelling, Davidson’s model, which was developed based on the inhalation of BTEX compounds, has been shown to be the most effective in terms of normalized contribution, with a value of 6.018 NTC. Mor & Ravindra conversely achieved the highest normalized contribution value of 8.75 NTC by addressing the environmental impacts of solid waste sites in low- and middle-income countries.
The findings of this study suggest that the evaluation of scientific impact should be informed not only by the accumulation of past citations, but also by the consideration of the annual impact rate and thematic intensity.
Furthermore, bibliometric findings are supported by content analyses of sectoral sources related to BTEX exposure and the analysis methods used.

3.11. Content Analysis Results Related to BTEX Exposure

3.11.1. Sectoral and Environmental Distribution of BTEX Exposure

The sectoral and environmental distributions of BTEX exposure were examined and are presented in Table 4.
Research conducted on the occupational and environmental effects of BTEX has demonstrated that long-term exposure engenders significant health risks for workers. For instance, observations from measurements of ambient air in automobile repair garages in Montreal, Canada, have demonstrated that multiple sources contribute to the occupational exposure of automobile repairers and painters to BTEX. Considering the toxicological implications of these chemicals, a comprehensive evaluation has been conducted to ascertain the chronic non-cancer hazards and the lifetime cancer risk associated with exposure to these chemicals within the specified occupational group. Even though the BTEX levels measured in all garages were below the limits set for occupational exposure, benzene levels have been shown to pose a potential cancer risk for workers. Although the emergence of chronic non-cancer health problems is not expected at dominant BTEX levels, this situation presents a risk that must be carefully monitored in terms of occupational safety [61].

3.11.2. Devices, Detectors, and Sampling Methods Used in BTEX Analysis

The classification of methods employed for the analysis of BTEX compounds in indoor environments is shown in Table 5.
The assessment of respiratory and dermal exposure, particularly in relation to individuals employed in industrial areas, is directly related to the effectiveness of occupational health and safety practices. In this context, the sensitivity, portability, and analytical capacity of the measurement methods employed are of pivotal significance to both field applications and laboratory studies. The selection of methods for BTEX analysis varies depending on the physicochemical properties of the target compound, environmental conditions, and the purpose of the monitoring.

3.11.3. Monitoring BTEX Exposure with Biological Markers

Analyses conducted on biological samples are shown in Figure 11. These analyses were used to assess exposure to BTEX components.
Biological monitoring techniques facilitate the timely identification of potential health risks associated with exposure to BTEX, particularly in industrial and occupational contexts. These methods also provide a scientific foundation for the development of protective measures. In this context, the presence of toluene and xylene can be detected in blood samples. The presence of all BTEX compounds can be detected in urine samples [68]. This is an updated evaluation of the relationship between outdoor and indoor environments regarding BTEX exposure, with particular emphasis on the widespread use of urinary metabolites in biological monitoring [69].

4. Conclusions

This study systematically reveals the variability of BTEX (benzene, toluene, ethylbenzene and xylene) in environmental and indoor conditions, how people are exposed to it, and the potential health effects of this exposure. Considering the findings obtained, a comprehensive examination of the prominent articles was conducted, and a synopsis of the most salient findings is presented in the conclusion section.
The time series analyses presented in Figure 2 reveal a marked increase and structural transformation in publications on BTEX during the period 2010–2025; however, they also indicate that significant gaps remain in the literature despite growing academic interest.
As presented in Figure 7a,b and Figure 9, and Table 4, the findings indicate that BTEX compounds are emitted into the atmosphere from a wide range of sources, including storage facilities, petroleum refineries, industrial areas, urban zones with heavy traffic, and enclosed environments. It has been observed that higher temperatures, especially in summer, increase the evaporation rate, leading to significantly higher concentrations of toluene and ethylbenzene in refineries and other industrial sites. However, it has been found that the increases observed during nighttime hours are related to the weakening of atmospheric mixing conditions and the slowing of photochemical reactions. This demonstrates that BTEX exhibits significant daily and seasonal variations, indicating that temporal factors must be considered in health risk assessments.
The findings presented in Figure 6 and Table 4 demonstrate that indoor studies reveal a significant increase in VOC concentrations, particularly in environments with new furniture, post-renovation homes, settings where materials such as paint and adhesives are used, and during periods when heating systems are in operation.
The findings presented in Figure 6 and Figure 7a,b, and Table 3 demonstrate that prolonged exposure in confined environments can lead to serious health concerns, including headaches, respiratory disorders, and an elevated risk of cancer. Furthermore, the necessity of regular monitoring of indoor air quality is emphasized as a means of safeguarding workers’ occupational health and safety. The observation that certain measured BTEX levels exceed both national and international limit values underscores the imperative of prioritizing risk mitigation for public health and workplace environments.
As illustrated in Figure 7a,b and Table 5, the use of disparate measurement methods can be attributed to methodological discrepancies inherent in the respective studies, including factors such as sampling periods, devices employed, and analytical approaches. This situation complicates direct comparison and limits the generalizability of assessments regarding the health effects of BTEX. However, the classification of benzene as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC), together with the observation that critical thresholds are exceeded in the majority of studies, underscores the imperative for continuous monitoring of environmental and indoor air quality.
Finally, a comprehensive approach in health risk assessments is necessitated by the temporal and spatial variability exhibited by BTEX compounds in environmental and indoor settings. Regular monitoring, effective ventilation systems, structural improvements and policy developments that align with international standards are all vital for reducing exposure to BTEX in environmental and occupational health contexts. Future research conducted across different climatic periods, broad geographic areas and diverse sample groups will make a significant contribution to protecting public health and ensuring sustainable workplace safety.

Author Contributions

A.G. conceived and designed the project; A.G., M.O. and H.Y. analyzed the data; A.G. and H.H.D. interpreted the data; A.G., H.H.D. and H.Ç. wrote the paper; A.G. and G.D. supervised the project. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in this study are included in the article.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Flowchart of data collection, data analysis, and data visualization.
Figure 1. Flowchart of data collection, data analysis, and data visualization.
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Figure 2. Annual scientific production.
Figure 2. Annual scientific production.
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Figure 3. Most relevant sources.
Figure 3. Most relevant sources.
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Figure 4. Average citations per year.
Figure 4. Average citations per year.
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Figure 5. Visual representation of keyword distribution. (a) Treemap showing frequency and thematic clustering of terms. (b) Word cloud highlighting dominant concepts and associations.
Figure 5. Visual representation of keyword distribution. (a) Treemap showing frequency and thematic clustering of terms. (b) Word cloud highlighting dominant concepts and associations.
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Figure 6. Thematic map.
Figure 6. Thematic map.
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Figure 7. Coupling-based clustering results. (a) Strategic coupling map of thematic clusters. (b) Network visualization of co-coupled documents.
Figure 7. Coupling-based clustering results. (a) Strategic coupling map of thematic clusters. (b) Network visualization of co-coupled documents.
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Figure 8. Co-citation Network.
Figure 8. Co-citation Network.
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Figure 9. Countries’ Scientific Production.
Figure 9. Countries’ Scientific Production.
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Figure 10. Three-Field Plot: Relationship Diagram Between Author, Keyword, and Sources.
Figure 10. Three-Field Plot: Relationship Diagram Between Author, Keyword, and Sources.
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Figure 11. Monitoring of BTEX components in the human body. (Arrows indicate the detection of BTEX compounds in blood and urine samples.).
Figure 11. Monitoring of BTEX components in the human body. (Arrows indicate the detection of BTEX compounds in blood and urine samples.).
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Table 1. Prominent exposure limit values for BTEX constituents.
Table 1. Prominent exposure limit values for BTEX constituents.
ComponentACGIH TLV (TWA)OSHA PELNIOSH RELSTEL
(ACGIH)		STEL (OSHA)
Benzene0.5 ppm (1.6 mg m−3)1 ppm (3.2 mg m−3)0.1 ppm (0.32 mg m−3)2.5 ppm-
Toluene20 ppm (75 mg m−3)200 ppm (750 mg m−3)100 ppm (375 mg m−3)150 ppm-
Etilbenzene20 ppm (87 mg m−3)100 ppm (435 mg m−3)100 ppm (435 mg m−3)125 ppm-
Xylene100 ppm (434 mg m−3)100 ppm (435 mg m−3)100 ppm (435 mg m−3)150 ppm-
TWA = Time-Weighted Average; STEL = Short-Term Exposure Limit; OSHA PEL = Occupational Safety and Health Administration Permissible Exposure Limit; NIOSH REL = National Institute for Occupational Safety and Health Recommended Exposure Limit.
Table 2. Overview of the research data.
Table 2. Overview of the research data.
Description
Main Information About Data		Results
Timespan2010:2025
Sources (Journals, Books, etc.)88
Documents269
Annual Growth Rate %12.37
Document Average Age4.58
Average citations per doc23.97
References10,160
Document Contents
Keywords Plus (ID)702
Author’s Keywords (DE)766
Authors
Authors1339
Authors of single-authored docs3
Author Collaboration
Single-authored docs3
Co-Authors per Doc6.42
International co-authorships %29.74
Document Types
Research article269
Table 3. Most Influential Authors and Publications in the Field of BTEX Exposure.
Table 3. Most Influential Authors and Publications in the Field of BTEX Exposure.
AuthorsTitleTCTCperYearNTC
Durmusoglu et al., 2010 [2]Health risk assessment of BTEX emissions in the landfill environment31919.9382.482
Dai et al., 2017 [38]VOC characteristics and inhalation health risks in newly renovated residences in Shanghai, China17319.2224.834
Tiwari et al., 2010 [39]Ambient levels of volatile organic compounds in the vicinity
of petrochemical industrial area of Yokohama, Japan		1529.51.183
Pinedo et al., 2013 [40]Assessment of soil pollution based on total petroleum hydrocarbons and individual oil substances13910.6923.109
Davidson et al., 2021 [8]Effects of inhaled combined Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX): Toward an environmental exposure model13226.46.018
Mor and Ravindra, 2023 [41]Municipal solid waste landfills in lower- and middle-income countries: Environmental impacts, challenges and sustainable management practices12441.3338.75
Hazrati et al., 2016 [42]Preliminary assessment of BTEX concentrations in indoor air of residential buildings and atmospheric ambient air in Ardabil, Iran11211.22.638
Li et al., 2014 [43]Pollution characteristics and health risk assessment of benzene homologues in ambient air in the northeastern urban area of Beijing, China1089.01.788
Wu et al., 2018 [44]Assessment of the health risks and odor concentration of volatile compounds from a municipal solid waste landfill in China10312.8752.321
Zhao et al., 2019 [45]Interaction of inhalable volatile organic compounds and pulmonary surfactant: Potential hazards of VOCs exposure to lung10214.5712.618
TC: Total Citation. TCperYear: Yearly Average Citations. NTC: Normalized Citation. * The top 10 authors and their works with the most citations in the dataset are provided.
Table 4. Industrial and environmental sources of BTEX exposure.
Table 4. Industrial and environmental sources of BTEX exposure.
Industry/EnvironmentBTEX-Containing MaterialsCommon Areas of Use/Sources
Home/Interior [46]Paint, varnish, cleaning materialsNewly painted walls, carpets, furniture, cleaning products
Industry [47,48]Paint, varnish, coating materialsProduction lines, assembly areas, automotive industry, construction sites
Waste Facility [49]Plastic, polymer, waste materialsWaste storage areas, recycling facilities, waste processing areas
Hookah Cafes [50,51]Tobacco products, hookah accessoriesAreas where hookah is smoked, sources of tobacco smoke
Transportation/Automotive Industry [52,53]Vehicle interior materials, fuelsGas stations, vehicle interiors, buses, taxis
Educational Institutions [54,55]Plastic, paint, cleaning suppliesSchool buildings, classrooms, laboratories
Gas Stations [56,57]Gasoline, diesel, LPGFueling areas, pumps, storage areas
Food Industry [58]Packaging materials, cleaning productsFood production facilities, storage areas, restaurants
Electronic Waste [59]E-waste, circuit boards, plasticsElectronic waste recycling facilities, storage areas
Beauty Salon [60]Paint, tobacco products, cleaning suppliesManicure/pedicure areas, tobacco smoke sources, cleaning products
Table 5. BTEX Analysis Methods.
Table 5. BTEX Analysis Methods.
Method NameExplanation
Gas Chromatography (GC) [62,63]This method is frequently employed in the separation and detection of volatile organic compounds.
Mass Spectrometry (MS) [34,64]The combination of gas chromatography-mass spectrometry (GC-MS) is utilized for the determination of the structural composition and quantitative analysis of components.
Flame Ionization Detector (FID) [43,65]The utilization of this method in conjunction with GC is a process of paramount importance in the detection of organic compounds.
Gas Chromatography–Photoionization Detector (GC–PID) [66] GC–PID is a technique that offers rapid analysis capabilities and can be used for both online and offline measurements.
Activated Carbon Tube and Pump [67]Used for collecting and analyzing air samples.
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MDPI and ACS Style

Gökcan, A.; Demir, H.H.; Ozdemir, M.; Yasa, H.; Çelikten, H.; Demir, G. Occupational and Environmental BTEX Exposure: A Bibliometric Analysis Using Scientific Mapping. Atmosphere 2025, 16, 1353. https://doi.org/10.3390/atmos16121353

AMA Style

Gökcan A, Demir HH, Ozdemir M, Yasa H, Çelikten H, Demir G. Occupational and Environmental BTEX Exposure: A Bibliometric Analysis Using Scientific Mapping. Atmosphere. 2025; 16(12):1353. https://doi.org/10.3390/atmos16121353

Chicago/Turabian Style

Gökcan, Ahmet, Hacer Handan Demir, Mükerrem Ozdemir, Hüdanur Yasa, Hakan Çelikten, and Göksel Demir. 2025. "Occupational and Environmental BTEX Exposure: A Bibliometric Analysis Using Scientific Mapping" Atmosphere 16, no. 12: 1353. https://doi.org/10.3390/atmos16121353

APA Style

Gökcan, A., Demir, H. H., Ozdemir, M., Yasa, H., Çelikten, H., & Demir, G. (2025). Occupational and Environmental BTEX Exposure: A Bibliometric Analysis Using Scientific Mapping. Atmosphere, 16(12), 1353. https://doi.org/10.3390/atmos16121353

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