Welding processes generate complex aerosols containing fine and ultrafine particulate matter, metal fumes, and gaseous by-products that may pose significant respiratory risks for exposed workers. Exhaled breath condensate (EBC) has emerged as a promising non-invasive matrix for human biomonitoring, offering the opportunity to assess exposure directly at the pulmonary target site and to evaluate early biological responses. This study systematically reviewed the scientific literature available in PubMed, Scopus, and ISI Web of Science to examine the role of EBC in exposure and effect biomonitoring among welders. Sixteen studies met the inclusion criteria. Overall, the evidence indicates that EBC is a suitable matrix for assessing occupational exposure in welding activities. Several studies reported increased concentrations of metals-including Manganese, Nickel, Iron, and Chromium in welders compared to unexposed controls, as well as higher post‐shift levels compared with pre‐shift samples across the workweek. Associations between cumulative exposure to inhalable dust and metal concentrations in EBC were also observed, even at low exposure levels. EBC has additionally shown potential for detecting early-effect biomarkers, such as indicators of oxidative stress, lipid peroxidation, protein and nucleic acid oxidation, and inflammatory mediators. These findings provide insight into biochemical alterations occurring in the airway lining fluid of welders. Despite encouraging findings, key methodological issues persist. The lack of standardized protocols for EBC collection, storage, and analysis hampers comparability across studies. Indeed, further research should elucidate EBC production and dilution kinetics and clarify metal toxicokinetics to fully establish EBC as a reliable biomonitoring matrix for occupational health research and practice.
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ISSN: 1752-7163
This journal is dedicated to all aspects of breath science, with the major focus on analysis of exhaled breath in physiology and medicine, and the diagnosis and treatment of breath odours.
Official Journal of the International Association for Breath Research (IABR).
- The following article is Open accessWelding activities: is EBC a reliable indicator for assessing metal exposure or early biological effects? A systematic review
Veruscka Leso et al 2026 J. Breath Res. 20 034001
- The following article is Open accessAnalysis of fetal DNA in biological samples derived from maternal exhaled breath
Erkam Dolapci et al 2026 J. Breath Res. 20 036007
View article, Analysis of fetal DNA in biological samples derived from maternal exhaled breathPDF, Analysis of fetal DNA in biological samples derived from maternal exhaled breathObjective. Detection of cell-free fetal DNA (cffDNA) in maternal plasma has paved the way for non-invasive prenatal testing. The ability to detect cffDNA in various body fluids has increased interest in alternative sampling methods. Exhaled breath condensate (EBC) is a non-invasive specimen that allows analysis of genetic materials such as DNA and RNA. This study aimed to investigate the presence of fetal DNA in EBC samples from pregnant women. Materials And Methods. Thirty pregnant women carrying male fetuses as confirmed by routine ultrasonography were included in the study. EBC samples were collected, and DNA was extracted. The presence of the SRY gene was analyzed using digital droplet PCR. Results. The mean maternal age was 30.1 years, mean gestational age was 37 weeks, and mean DNA concentration was 17 ng µl−1. The SRY gene was detected in 11–30 samples (36.6%). All newborns were phenotypically male. Conclusion. This study demonstrates the detectability of fetal DNA in EBC samples from pregnant women and supports the feasibility of EBC as a novel non-invasive sampling matrix for prenatal genetic analysis. Although further methodological optimization is required, these findings highlight the potential of EBC as an alternative source of fetal genetic material for future prenatal testing applications.
- The following article is Open accessMultifactorial assessment of halitosis in systemically and orally healthy orthodontic patients: airway dimensions, breathing pattern, and comparison with a portable breath analyzer
İsmail Ongun et al 2026 J. Breath Res. 20 036006
View article, Multifactorial assessment of halitosis in systemically and orally healthy orthodontic patients: airway dimensions, breathing pattern, and comparison with a portable breath analyzerPDF, Multifactorial assessment of halitosis in systemically and orally healthy orthodontic patients: airway dimensions, breathing pattern, and comparison with a portable breath analyzerHalitosis is a multifactorial condition influenced by airway-related factors and breathing patterns. This study aimed to evaluate the relationship between airway dimensions, craniofacial morphology, and breathing type with halitosis in orthodontic patients. In addition, the agreement between the portable breath analyzer and the organoleptic method, as well as the role of self-reported and physiological halitosis, was investigated. This cross-sectional study included 113 systemically and orally healthy orthodontic patients. Lateral cephalometric radiographs were used to assess the sagittal and vertical skeletal patterns and pharyngeal airway dimensions. Halitosis was evaluated using an organoleptic method as the reference standard and a portable breath analysis device for comparison. Oral hygiene habits, breathing type, and perception of halitosis were recorded using a structured questionnaire. Statistical analyses included appropriate parametric and nonparametric tests as well as multivariate logistic regression. Agreement was assessed using Cohen’s kappa coefficient. The overall prevalence of halitosis was 8.9% based on organoleptic assessment. Tooth brushing frequency (p = 0.041) and oral dryness (p = 0.004) were significantly associated with halitosis, whereas airway dimensions, skeletal patterns, and breathing types were not (p > 0.05). Physiological halitosis (p = 0.003) and oral dryness (p = 0.047) were significant predictors of self-reported halitosis. The agreement between the self-reported and objective measurements was weak (κ = 0.264; p < 0.001). A statistically significant and substantial level of agreement was observed between the portable device and the organoleptic assessment (κ = 0.698). Airway-related parameters were not identified as significant determinants of halitosis. Within the limitations of this study, halitosis was more closely associated with self-reported oral dryness and tooth-brushing frequency than with airway morphology. Portable breath analyzers may serve as practical adjunctive tools for clinical assessments when used under standardized conditions.
- The following article is Open accessFrom dysbiotic gut to malodorous mouth: targeting microbial metabolism for gastrointestinal type halitosis
Xin Liang et al 2026 J. Breath Res. 20 034003
View article, From dysbiotic gut to malodorous mouth: targeting microbial metabolism for gastrointestinal type halitosisPDF, From dysbiotic gut to malodorous mouth: targeting microbial metabolism for gastrointestinal type halitosisThis article reviews the microbiological mechanisms of halitosis, the oral-gut axis, the role of the gut microbiome, related metabolic pathways, and their associations with gastrointestinal diseases, and explores intervention strategies based on microbial regulation. Halitosis is primarily caused by volatile sulfur compounds produced by oral microorganisms, especially gram-negative anaerobic bacteria, and volatile organic compounds in most extraoral etiologies. Studies have found that intestinal microbial dysregulation can affect the composition of oral flora through the oral-gut axis and aggravate bad breath. Gastrointestinal diseases, such as gastroesophageal reflux disease, Helicobacter pylori infection, ulcerative colitis and irritable bowel syndrome can directly or indirectly promote the occurrence of bad breath by changing the intestinal microenvironment and microbial metabolic pathways, such as protein spoilage or short-chain fatty acids imbalance, etc. For microbial interventions, traditional Chinese medicine can not only systemically regulate the oral-gut axis balance, but also effectively alleviate bad breath by targeting sterilization and inhibiting the metabolic activity of pathogenic bacteria. This review focuses on elucidating the complex links between halitosis and the gut microbiome, its metabolic pathways, and gastrointestinal diseases, emphasizing the key role of microbial metabolites in pathological mechanisms. It reveals the importance of the oral-gut axis in systemic health and provides a rationale for developing personalized halitosis management strategies based on microbiome regulation.
- The following article is Open accessA novel approach to non-invasive lung cancer screening via exhaled breath analysis using proton transfer reaction time-of-flight mass spectrometry
Maribel Hernández-Camarillo et al 2026 J. Breath Res. 20 036008
View article, A novel approach to non-invasive lung cancer screening via exhaled breath analysis using proton transfer reaction time-of-flight mass spectrometryPDF, A novel approach to non-invasive lung cancer screening via exhaled breath analysis using proton transfer reaction time-of-flight mass spectrometryLung cancer (LC) remains a global public health problem. To minimize late diagnosis, new detection techniques are needed. The analysis of volatile organic compounds (VOCs) in human breath (the volatilome) represents a non-invasive alternative to current methods for the early detection of LC. In this study, VOCs were determined in the breath of individuals with LC (N = 22) and without LC (non-LC, N = 21) using proton transfer reaction time-of-flight mass spectrometry. Orthogonal partial least squares discriminant analysis and hierarchical cluster analysis were conducted on a subset of 54 VOC ions (out of 180). Twenty-one of the 54 VOC ions were detected in exhaled breath. CH4O3H+ and C8H7NH+ were found only in participants without cancer. Among the 19 common ions present in both cohorts, the intensities of 8 ions were statistically different. The LC/non-LC ratios were observed for C4H8O2H+, followed by C3H4OH+, C2H2OH+, C2H3ONH+, C3H4H+, C3H2H+, C4H8H+, and C6H8H+. Spearman correlation analysis could be used to differentiate metabolic processes or pathways between cohorts. Diagnostic ratio is a potential tool to classify individuals with or without LC. This study provides exploratory evidence for exhaled VOCs as potential LC biomarkers and positions them as a complement to current diagnostic pathways, with a potential role in supporting early triage and clinical decision-making.
- The following article is Open accessVolatile compounds in human breath: critical review and meta-analysis
Theo Issitt et al 2022 J. Breath Res. 16 024001
View article, Volatile compounds in human breath: critical review and meta-analysisPDF, Volatile compounds in human breath: critical review and meta-analysisVolatile compounds contained in human breath reflect the inner workings of the body. A large number of studies have been published that link individual components of breath to disease, but diagnostic applications remain limited, in part due to inconsistent and conflicting identification of breath biomarkers. New approaches are therefore required to identify effective biomarker targets. Here, volatile organic compounds have been identified in the literature from four metabolically and physiologically distinct diseases and grouped into chemical functional groups (e.g. methylated hydrocarbons or aldehydes; based on known metabolic and enzymatic pathways) to support biomarker discovery and provide new insight on existing data. Using this functional grouping approach, principal component analysis doubled explanatory capacity from 19.1% to 38% relative to single individual compound approaches. Random forest and linear discriminant analysis reveal 93% classification accuracy for cancer. This review and meta-analysis provides insight for future research design by identifying volatile functional groups associated with disease. By incorporating our understanding of the complexities of the human body, along with accounting for variability in methodological and analytical approaches, this work demonstrates that a suite of targeted, functional volatile biomarkers, rather than individual biomarker compounds, will improve accuracy and success in diagnostic research and application.
- The following article is Open accessThe advantages of standardizing exhaled breath-alcohol concentration to a reference respiratory gas—water vapor
Lars Lindberg and Alan Wayne Jones 2023 J. Breath Res. 17 014002
View article, The advantages of standardizing exhaled breath-alcohol concentration to a reference respiratory gas—water vaporPDF, The advantages of standardizing exhaled breath-alcohol concentration to a reference respiratory gas—water vaporMeasuring the concentration of alcohol (ethanol) in exhaled breath (BrAC) provides a rapid and non-invasive way to determine the co-existing concentration in arterial blood (A-BAC). The results of breath-alcohol testing are used worldwide as evidence of excessive drinking, such as when traffic offenders are prosecuted. Two types of breath-alcohol analyzer are in common use; hand-held instruments used as preliminary screening tests of sobriety and more sophisticated evidential instruments, the results of which are accepted as evidence for prosecution of drunken drivers. Most evidential breath-alcohol analyzers are designed to capture the last portion of a prolonged exhalation, which is thought to reflect the alcohol concentration in substantially alveolar air. The basic premise of breath-alcohol analysis is that there is a physiological relationship between A-BAC and BrAC and close agreement between the two analytical methods. This article reviews the principles and practice of breath-alcohol analysis and introduces the concept of standardizing the results to a secondary physiological gas (water vapor), which therefore serves as an internal standard. The measured BrAC is thus adjusted to an alveolar air water content of 43.95 mg l−1 at 37 °C. This has several advantages, and means that a sample of breath can be captured without the person having to blow directly into the instrument. Adjusting the breath-alcohol concentration to water vapor concentration also compensates for variations in temperature of the expired air. The contact-free method of sampling breath means that a mouthpiece is unnecessary and the test subject does not need to make a continuous end exhalation.
- The following article is Open accessBreath acetone as a potential marker in clinical practice
Veronika Ruzsányi and Miklós Péter Kalapos 2017 J. Breath Res. 11 024002
View article, Breath acetone as a potential marker in clinical practicePDF, Breath acetone as a potential marker in clinical practiceIn recent decades, two facts have changed the opinion of researchers about the function of acetone in humans. Firstly, it has turned out that acetone cannot be regarded as simply a waste product of metabolism, because there are several pathways in which acetone is produced or broken down. Secondly, methods have emerged making possible its detection in exhaled breath, thereby offering an attractive alternative to investigation of blood and urine samples. From a clinical point of view the measurement of breath acetone levels is important, but there are limitations to its wide application. These limitations can be divided into two classes, technical and biological limits. The technical limits include the storage of samples, detection threshold, standardization of clinical settings, and the price of instruments. When considering the biological ranges of acetone, personal factors such as race, age, gender, weight, food consumption, medication, illicit drugs, and even profession/class have to be taken into account to use concentration information for disorders. In some diseases such as diabetes mellitus and lung cancer, as well as in nutrition-related behavior such as starvation and ketogenic diet, breath acetone has been extensively examined. At the same time, there is a lack of investigations in other cases in which ketosis is also evident, such as in alcoholism or an inborn error of metabolism. In summary, the detection of acetone in exhaled breath is a useful and promising tool for diagnosis and it can be used as a marker to follow the effectiveness of treatments in some disorders. However, further endeavors are needed for clarification of the exact distribution of acetone in different body compartments and evaluation of its complex role in humans, especially in those cases in which a ketotic state also occurs.
- The following article is Open accessFeasibility study on training dogs to detect lung cancer: findings of a retrospective evaluation
Christian Grah et al 2026 J. Breath Res. 20 026008
View article, Feasibility study on training dogs to detect lung cancer: findings of a retrospective evaluationPDF, Feasibility study on training dogs to detect lung cancer: findings of a retrospective evaluationEarly detection is critical for lung cancer patients. One lung cancer detection method under study is using sniffer dogs. This study aimed to evaluate, retrospectively, the sensitivity and specificity of the Cancer Detection Dog Collective (CDDC®) method under training conditions. A team of five trained sniffer dogs analyzed breath samples from lung cancer patients and cancer-free volunteers, and a cancer sample is positive if at least three dogs indicate it. Dog handlers and experimental observers were blinded to sample identity, and detection accuracy was assessed. Primary endpoint was sensitivity, and specificity and confounding factors were also assessed. Samples were collected in 2024 from 824 volunteers, including 111 with a confirmed diagnosis of lung cancer (mean age 60, range 34–80, 18% early-stage cancer, 46% not yet oncological treated). A total of 11 900 breath samples were tested with 125 test runs per dog. Each of the five dogs demonstrated a detection performance with a sensitivity between 82% and 89%, a specificity over 95%, and an accuracy over 94%. The CDDC® dog team’s corporate decision revealed a sensitivity of at least 95.5%. The cancer-free volunteers were primarily young, healthy individuals. According to the CDDC® decision rules, none of these control samples were identified as false positives by more than two dogs. Analysis of potential confounding factors revealed that weather conditions and supervisor skills were associated with the dogs’ performance. The CDDC® method showed high consistency in training scenarios. Further studies should evaluate this method in a controlled clinical study alongside lung cancer screening.
- The following article is Open accessEvaluation of natural products for anti-halitosis activity based on methyl mercaptan inhibition
Bok Hee Woo et al 2026 J. Breath Res. 20 026002
View article, Evaluation of natural products for anti-halitosis activity based on methyl mercaptan inhibitionPDF, Evaluation of natural products for anti-halitosis activity based on methyl mercaptan inhibitionHalitosis, or oral malodour, is primarily caused by volatile sulphur compounds (VSCs) such as methyl mercaptan, which are produced by anaerobic bacteria including Porphyromonas gingivalis (P. gingivalis) and Fusobacterium nucleatum (F. nucleatum). While conventional antibacterial mouthwashes are widely used, their adverse effects—such as microbial imbalance and dental staining—necessitate safer, natural alternatives. This study aimed to identify plant-derived agents with anti-halitosis, antibacterial, and anti-inflammatory activity, with low cytotoxicity. A total of 252 medicinal plant extracts were screened for biological activity. Antibacterial effects against P. gingivalis and F. nucleatum were evaluated using spectrophotometry and agar well diffusion assays. Anti-inflammatory activity was assessed by nitric oxide inhibition in LPS-stimulated macrophages. Cytotoxicity was measured in gingival epithelial cells and oral keratinocytes. The anti-halitosis effect was determined based on inhibition of methyl mercaptan production using Oral Chroma, a gas chromatography–based device. Of the 252 extracts, 32 demonstrated significant antibacterial activity, VSC suppression, and low cytotoxicity. Among these, Polygoni Cuspidati Radix, Rhei Rhizoma, Pini Ramulus, and Piperis Longi Fructus exhibited the most potent inhibition of methyl mercaptan production. Combination treatments using these extracts maintained efficacy at lower concentrations. The findings suggest that these herbal extracts may serve as effective, safe, and accessible anti-halitosis agents. Their dual antibacterial and anti-inflammatory effects support their potential use in oral hygiene formulations, offering a natural alternative for the prevention and management of halitosis.
- The following article is Open accessDiagnosing melioidosis and tracking treatment outcomes using breath
Antao Gao et al 2026 J. Breath Res. 20 036010
View article, Diagnosing melioidosis and tracking treatment outcomes using breathPDF, Diagnosing melioidosis and tracking treatment outcomes using breathMelioidosis is a life-threatening infectious disease caused by Burkholderia pseudomallei (Bp). Rapid diagnosis and appropriate antimicrobial treatment are critical to reduce mortality, yet diagnosis is hindered by diverse clinical manifestations, mimicry with other diseases, and reliance on slow culture-based methods. Detecting volatile compounds offers a non-invasive approach for rapid infection detection. In this study, we aim to identify volatile compounds in patients’ breath that can aid in diagnosing melioidosis and indicating response to treatment. Breath samples were collected from 17 patients with culture-confirmed melioidosis and eight patients with other febrile illnesses. Longitudinal samples were collected from five of the 17 melioidosis patients over approximately one month of antibiotic treatment. Breath samples were analyzed using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry. Data analysis involved statistical comparison and machine learning–based feature selection. We identified three breath markers—camphene, 1-butanol, and 3-methylheptyl acetate—that discriminated melioidosis (n = 7) from febrile controls (n = 6) with an area under the receiver operating characteristic curve of 1.00. These three markers correctly classified 11 additional samples from 11 melioidosis patients, with one febrile control misclassified. Separately, we selected four breath markers, three of which were hydrocarbons, that differentiated samples associated with a positive Bp culture from those with a negative Bp culture, with a random forest model developed upon these four markers showing a sensitivity of 98% and specificity of 95%. Moreover, we identified a set of 16 volatile compounds that significantly correlated (correlation coefficient > 0.6) with blood C-reactive protein levels. Lastly, a panel of 144 volatile compounds was identified that corresponded to treatment time, indicating that the breath profile may reflect treatment response or shifts in disease severity. This pilot study reports candidate breath-based markers for diagnosing melioidosis and assessing treatment outcome, supporting further validation in larger studies.
- The following article is Open accessDirect sampling of the peripheral lung identifies lung-derived volatile organic compounds detectable in exhaled breath: a feasibility study
Renelle Myers et al 2026 J. Breath Res. 20 036009
View article, Direct sampling of the peripheral lung identifies lung-derived volatile organic compounds detectable in exhaled breath: a feasibility studyPDF, Direct sampling of the peripheral lung identifies lung-derived volatile organic compounds detectable in exhaled breath: a feasibility studyExhaled breath (EB) testing holds potential for non-invasive screening and early detection of lung cancer. Development of such a test requires knowledge of volatile organic compounds (VOCs) originating in the lung microenvironment, rather than exogenous sources or non-lung endogenous sources such as the GI tract and oral cavity. Direct evidence linking peripheral lung-derived VOCs to EB is lacking. The peripheral lung air (⩾4th generation airways) of thirty-five participants (9 lung cancers; 26 controls) was sampled during bronchoscopy using micro-thermal desorption-gas chromatography-ion mobility spectrometry (µTD-GC-IMS) for direct on-site analysis and was compared to EB obtained immediately prior. Data processing included signal-normalized background subtraction to evaluate which VOCs originate in the peripheral lung and comparison to EB. Forty-three IMS clusters (features) were determined to originate from the lung microenvironment. All forty-three lung-originating features were detected in EB. Twenty-four out of forty-three features had higher median signal in either the EB or peripheral lung air compared to the environmental background. Some features had higher signal in EB compared to peripheral lung air, while others showed the reverse trend. Direct analysis of peripheral lung air, proximal to the tumour, using µTD-GC-IMS was clinically feasible. These findings help address a key translational barrier in breath-based respiratory biomarker development and support the feasibility of non-invasive approaches for lung cancer screening grounded in lung-specific VOC biology, and will inform larger clinical trials directed at breath biomarker discovery.
- Comment on ‘case-control study related to the use of L-cysteine in the differential diagnosis of oral halitosis’
Xiao Xian Qian 2026 J. Breath Res. 20 038001
- Reply to comment on ‘case-control study related to the use of L-cysteine in the differential diagnosis of oral halitosis’
Guilherme Simpione et al 2026 J. Breath Res. 20 038002
- The following article is Open accessA novel approach to non-invasive lung cancer screening via exhaled breath analysis using proton transfer reaction time-of-flight mass spectrometry
Maribel Hernández-Camarillo et al 2026 J. Breath Res. 20 036008
View article, A novel approach to non-invasive lung cancer screening via exhaled breath analysis using proton transfer reaction time-of-flight mass spectrometryPDF, A novel approach to non-invasive lung cancer screening via exhaled breath analysis using proton transfer reaction time-of-flight mass spectrometryLung cancer (LC) remains a global public health problem. To minimize late diagnosis, new detection techniques are needed. The analysis of volatile organic compounds (VOCs) in human breath (the volatilome) represents a non-invasive alternative to current methods for the early detection of LC. In this study, VOCs were determined in the breath of individuals with LC (N = 22) and without LC (non-LC, N = 21) using proton transfer reaction time-of-flight mass spectrometry. Orthogonal partial least squares discriminant analysis and hierarchical cluster analysis were conducted on a subset of 54 VOC ions (out of 180). Twenty-one of the 54 VOC ions were detected in exhaled breath. CH4O3H+ and C8H7NH+ were found only in participants without cancer. Among the 19 common ions present in both cohorts, the intensities of 8 ions were statistically different. The LC/non-LC ratios were observed for C4H8O2H+, followed by C3H4OH+, C2H2OH+, C2H3ONH+, C3H4H+, C3H2H+, C4H8H+, and C6H8H+. Spearman correlation analysis could be used to differentiate metabolic processes or pathways between cohorts. Diagnostic ratio is a potential tool to classify individuals with or without LC. This study provides exploratory evidence for exhaled VOCs as potential LC biomarkers and positions them as a complement to current diagnostic pathways, with a potential role in supporting early triage and clinical decision-making.
- The following article is Open accessFrom dysbiotic gut to malodorous mouth: targeting microbial metabolism for gastrointestinal type halitosis
Xin Liang et al 2026 J. Breath Res. 20 034003
View article, From dysbiotic gut to malodorous mouth: targeting microbial metabolism for gastrointestinal type halitosisPDF, From dysbiotic gut to malodorous mouth: targeting microbial metabolism for gastrointestinal type halitosisThis article reviews the microbiological mechanisms of halitosis, the oral-gut axis, the role of the gut microbiome, related metabolic pathways, and their associations with gastrointestinal diseases, and explores intervention strategies based on microbial regulation. Halitosis is primarily caused by volatile sulfur compounds produced by oral microorganisms, especially gram-negative anaerobic bacteria, and volatile organic compounds in most extraoral etiologies. Studies have found that intestinal microbial dysregulation can affect the composition of oral flora through the oral-gut axis and aggravate bad breath. Gastrointestinal diseases, such as gastroesophageal reflux disease, Helicobacter pylori infection, ulcerative colitis and irritable bowel syndrome can directly or indirectly promote the occurrence of bad breath by changing the intestinal microenvironment and microbial metabolic pathways, such as protein spoilage or short-chain fatty acids imbalance, etc. For microbial interventions, traditional Chinese medicine can not only systemically regulate the oral-gut axis balance, but also effectively alleviate bad breath by targeting sterilization and inhibiting the metabolic activity of pathogenic bacteria. This review focuses on elucidating the complex links between halitosis and the gut microbiome, its metabolic pathways, and gastrointestinal diseases, emphasizing the key role of microbial metabolites in pathological mechanisms. It reveals the importance of the oral-gut axis in systemic health and provides a rationale for developing personalized halitosis management strategies based on microbiome regulation.
- Advances in proton transfer reaction mass spectrometry-assisted breath analysis for disease diagnosis
Xin Guolin et al 2026 J. Breath Res. 20 034002
View article, Advances in proton transfer reaction mass spectrometry-assisted breath analysis for disease diagnosisPDF, Advances in proton transfer reaction mass spectrometry-assisted breath analysis for disease diagnosisProton transfer reaction mass spectrometry (PTR-MS) has emerged as a transformative tool in breath analysis, enabling real-time, high-sensitivity profiling of volatile organic compounds down to the pptv level without sample preparation. This review critically examines the technological evolution of PTR-MS, from fundamental ion–molecule kinetics to advanced configurations, including time-of-flight analyzers and switchable reagent ion technologies. We systematically evaluate the clinical potential of PTR-MS for identifying volatile signatures associated with pulmonary malignancies, infectious diseases, and systemic metabolic disorders. Despite these advances, the transition of PTR-MS from exploratory studies to routine clinical application remains limited by three major challenges: insufficient metrological traceability in quantification, qualitative ambiguity arising from isomeric overlap, and poor inter-study comparability caused by non-standardized sampling workflows. To bridge this trust gap, we propose a validation framework centered on traceable calibration, standardized breath sampling, and confidence-ranked qualitative confirmation. In particular, we advocate the use of matrix-matched reference materials for absolute quantification and the development of a standardized PTR-MS spectral atlas integrating GC retention information and reagent-ion-dependent fragmentation behavior. Such a metrological and harmonization-oriented strategy is essential for improving reproducibility, cross-platform comparability, and the clinical translation of PTR-MS in precision medicine.
- The following article is Open accessWelding activities: is EBC a reliable indicator for assessing metal exposure or early biological effects? A systematic review
Veruscka Leso et al 2026 J. Breath Res. 20 034001
View article, Welding activities: is EBC a reliable indicator for assessing metal exposure or early biological effects? A systematic reviewPDF, Welding activities: is EBC a reliable indicator for assessing metal exposure or early biological effects? A systematic reviewWelding processes generate complex aerosols containing fine and ultrafine particulate matter, metal fumes, and gaseous by-products that may pose significant respiratory risks for exposed workers. Exhaled breath condensate (EBC) has emerged as a promising non-invasive matrix for human biomonitoring, offering the opportunity to assess exposure directly at the pulmonary target site and to evaluate early biological responses. This study systematically reviewed the scientific literature available in PubMed, Scopus, and ISI Web of Science to examine the role of EBC in exposure and effect biomonitoring among welders. Sixteen studies met the inclusion criteria. Overall, the evidence indicates that EBC is a suitable matrix for assessing occupational exposure in welding activities. Several studies reported increased concentrations of metals-including Manganese, Nickel, Iron, and Chromium in welders compared to unexposed controls, as well as higher post‐shift levels compared with pre‐shift samples across the workweek. Associations between cumulative exposure to inhalable dust and metal concentrations in EBC were also observed, even at low exposure levels. EBC has additionally shown potential for detecting early-effect biomarkers, such as indicators of oxidative stress, lipid peroxidation, protein and nucleic acid oxidation, and inflammatory mediators. These findings provide insight into biochemical alterations occurring in the airway lining fluid of welders. Despite encouraging findings, key methodological issues persist. The lack of standardized protocols for EBC collection, storage, and analysis hampers comparability across studies. Indeed, further research should elucidate EBC production and dilution kinetics and clarify metal toxicokinetics to fully establish EBC as a reliable biomonitoring matrix for occupational health research and practice.
- The following article is Open accessSome crucial principles of exhaled breath volatile analysis
Lorenzo S Petralia et al 2026 J. Breath Res. 20 024001
View article, Some crucial principles of exhaled breath volatile analysisPDF, Some crucial principles of exhaled breath volatile analysisThis review addresses several important confounding factors that are often overlooked in the analysis of volatiles contained in exhaled breath, which, if ignored, will significantly limit the interpretation of volatile data from exhaled breath and thus prevent meaningful outcomes. Crucial confounding factors that tend to be neglected are those that influence the alveolar volatile concentrations according to the Farhi equation, namely cardiac output, alveolar ventilation, blood:air partition coefficients and mixed-venous blood volatile concentrations. Another potential confounding factor is associated with the contributions of volatiles produced in the oral cavity through microbial activity. In addition, the concentration of an exhaled breath volatile will be affected if that volatile is also present in the ambient inhaled air. The purpose of this review is to show how these confounding factors can be accounted for. We will demonstrate how mathematical modeling and an understanding of the Farhi equation aid in the interpretation of the exhaled breath volatile concentration measurements. We will discuss the limitations of the alveolar gradient method used to determine the effects of inhaled volatiles. An alternative method is presented that correctly allows for any inhaled volatile contribution to the exhaled concentration of that volatile. The review concludes with suggested recommendations that, if adopted, will improve the quality of breath data leading to an improved interpretation of exhaled volatiles.
- Applications and challenges of exhaled volatile organic compounds in critically ill patients
Longxin Li et al 2026 J. Breath Res. 20 014002
View article, Applications and challenges of exhaled volatile organic compounds in critically ill patientsPDF, Applications and challenges of exhaled volatile organic compounds in critically ill patientsEarly detection of critical illness is essential for timely intervention and improved outcomes. Conventional diagnostic methods, such as laboratory tests and imaging, are invasive and often delayed. In recent years, non-invasive monitoring approaches, particularly exhaled breath analysis, have gained attention in critical care. Various analytical platforms, including gas chromatography–mass spectrometry, proton transfer reaction mass spectrometry, and electronic nose systems, have been employed to identify volatile organic compound (VOC) patterns associated with acute conditions. Elevated aldehydes and ketones have been reported in ventilator-associated pneumonia, hydrocarbons such as octane in acute respiratory distress syndrome, and acetone in acute heart failure. These findings highlight the value of VOC-based approaches for early disease recognition, pathogen identification, and dynamic monitoring at the bedside. Exhaled breath analysis represents a promising, non-invasive tool to complement conventional diagnostics in the intensive care unit, though challenges such as standardization and large-scale validation remain. This review focuses on the application of VOCs in the management of critically ill patients, with special emphasis on their diagnostic and monitoring potential.
- The following article is Open accessSweet interference: oral fermentation volatile confounders in exhaled breath revealed by minimal glucose exposure
Chawaguta et al
View accepted manuscript, Sweet interference: oral fermentation volatile confounders in exhaled breath revealed by minimal glucose exposurePDF, Sweet interference: oral fermentation volatile confounders in exhaled breath revealed by minimal glucose exposureVolatile organic compounds (VOCs) in human breath have been explored as non-invasive
biomarkers for disease, including respiratory infections and cancer, yet very few breath tests have reached clinical validation and regulatory approval. A major barrier is the difficulty of identifying and controlling confounding factors
that affect volatile exhaled breath composition. A critical and overlooked confounder is the
oral microbiome, which produces VOCs that can obscure the trace volatiles originating from
the lower airways. To investigate this, we conducted an intervention study on sixteen healthy
volunteers, using real-time breath analysis, which demonstrates that oral microbiota rapidly
alter exhaled VOC profiles following a low-dose (0.5 g) oral glucose administration. Acetoin
levels respond promptly to glucose, confirming its oral microbial origin. However, pathogenic
bacteria resulting from respiratory infections can also produce acetoin, underscoring the
challenge of distinguishing sources of breath VOCs. Similarly, other volatiles, such as acetic
acid and ethanol, are also influenced by small glucose doses, complicating their use as
biomarkers in non-targeted volatilomic studies. Recognizing the metabolic context of each
volatile is essential to distinguish infection signals from physiological background. Beyond
serving as a cautionary note for exhaled breath research, these results may encourage the oral
health and dentistry communities to adopt breathomics analytical tools for rapid chairside
diagnostics, transforming respiratory confounders into clinical opportunities for dental care.
- Exhaled breath volatile organic compounds in cystic fibrosis: a systematic review
Mustafina et al
View accepted manuscript, Exhaled breath volatile organic compounds in cystic fibrosis: a systematic reviewPDF, Exhaled breath volatile organic compounds in cystic fibrosis: a systematic reviewBackground: Cystic fibrosis (CF) is a genetic disorder characterized by chronic airway infection and progressive lung damage. Early identification of biomarkers associated with respiratory pathogens and inflammatory processes is crucial for improving disease monitoring and guiding therapy. Analysis of volatile organic compounds (VOCs) in exhaled breath has emerged as a promising non-invasive approach for biomarker discovery.
Objective: This systematic review aimed to identify and summarize VOCs detected in the exhaled breath of patients with cystic fibrosis that may serve as potential clinical biomarkers. 
Methods: A systematic literature search was conducted in accordance with PRISMA guidelines across MEDLINE, Web of Science, SCOPUS, and Google Scholar, covering publications from 2000 to 2026. Studies comparing VOC profiles in patients with cystic fibrosis and control groups were included. The risk of bias in the included studies was assessed using the Newcastle–Ottawa Scale.
Results: Out of 431 identified records, 27 studies met the inclusion criteria and were included in the qualitative synthesis. These studies employed a variety of analytical platforms, including gas chromatography–mass spectrometry (GC-MS), selected-ion flow-tube mass spectrometry (SIFT-MS), proton transfer reaction mass spectrometry (PTR-MS), and nuclear magnetic resonance (NMR) metabolomics. Across all studies, a total of 121 VOCs were reported in association with cystic fibrosis. Several compounds, including hydrogen cyanide, 2-aminoacetophenone, pentane, and dimethyl sulfide, were repeatedly identified and may represent potential biomarkers related to bacterial colonization, oxidative stress, and inflammatory processes. However, substantial heterogeneity was observed among studies with respect to study design, patient populations, breath sampling protocols, and analytical methodologies.
Conclusion: Breath analysis based on volatile organic compounds represents a promising non-invasive approach for identifying biomarkers of cystic fibrosis and associated respiratory infections. Nevertheless, future progress in breathomics will primarily depend on improving methodological rigor rather than limiting the diversity of analytical platforms. Standardized breath sampling protocols, rigorous preprocessing workflows for mass spectrometry data, sufficiently powered multicenter studies, and external validation in independent patient cohorts are essential prerequisites for the clinical implementation of breath-based biomarkers.
- The following article is Open accessThe oral cavity as a bioreactor in halitosis
Marinis et al
View accepted manuscript, The oral cavity as a bioreactor in halitosisPDF, The oral cavity as a bioreactor in halitosisHalitosis is a prevalent yet often underestimated clinical condition with multifactorial etiology, predominantly arising from intra-oral sources such as periodontal disease, tongue coating and xerostomia. Central to its pathogenesis is the microbial degradation of sulfur-containing substrates, which lead to the production of volatile sulfur compounds and other volatile organic compounds responsible for the characteristic odor. These metabolites are produced by proteolytic anaerobes inhabiting the tongue dorsum, periodontal pockets as well as the dental plaque and predominantly exist as structured biofilms. This review examines halitosis through a systems-based lens, conceptualizing the oral cavity as a dynamic bioreactor governed by microbial consortia and their metabolic pathways, mass transport, enzymatic kinetics, as well as growth conditions attributed to microenvironmental factors. Modeling approaches are required to elucidate the intricate dynamics within oral biofilms, including the heterogeneous structural organization and the fundamental transport and metabolic processes occurring at the biofilm-bulk fluid interface and within the biofilm matrix. These interfacial processes, in turn, regulate the flux of volatile compounds into the oral air. Furthermore, associations between halitosis and dental pathologies, including gingivitis, periodontitis, and periodontal abscesses, are explored through microbial dysbiosis. The review also addresses contemporary management strategies including mechanical debridement, antimicrobial agents and probiotics. Understanding the biochemical, microbial and reactor-like behavior of the oral cavity is critical for the effective diagnosis, monitoring and treatment of halitosis in clinical and research settings.
- The following article is Open accessDiagnosing melioidosis and tracking treatment outcomes using breath
Antao Gao et al 2026 J. Breath Res. 20 036010
View article, Diagnosing melioidosis and tracking treatment outcomes using breathPDF, Diagnosing melioidosis and tracking treatment outcomes using breathMelioidosis is a life-threatening infectious disease caused by Burkholderia pseudomallei (Bp). Rapid diagnosis and appropriate antimicrobial treatment are critical to reduce mortality, yet diagnosis is hindered by diverse clinical manifestations, mimicry with other diseases, and reliance on slow culture-based methods. Detecting volatile compounds offers a non-invasive approach for rapid infection detection. In this study, we aim to identify volatile compounds in patients’ breath that can aid in diagnosing melioidosis and indicating response to treatment. Breath samples were collected from 17 patients with culture-confirmed melioidosis and eight patients with other febrile illnesses. Longitudinal samples were collected from five of the 17 melioidosis patients over approximately one month of antibiotic treatment. Breath samples were analyzed using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry. Data analysis involved statistical comparison and machine learning–based feature selection. We identified three breath markers—camphene, 1-butanol, and 3-methylheptyl acetate—that discriminated melioidosis (n = 7) from febrile controls (n = 6) with an area under the receiver operating characteristic curve of 1.00. These three markers correctly classified 11 additional samples from 11 melioidosis patients, with one febrile control misclassified. Separately, we selected four breath markers, three of which were hydrocarbons, that differentiated samples associated with a positive Bp culture from those with a negative Bp culture, with a random forest model developed upon these four markers showing a sensitivity of 98% and specificity of 95%. Moreover, we identified a set of 16 volatile compounds that significantly correlated (correlation coefficient > 0.6) with blood C-reactive protein levels. Lastly, a panel of 144 volatile compounds was identified that corresponded to treatment time, indicating that the breath profile may reflect treatment response or shifts in disease severity. This pilot study reports candidate breath-based markers for diagnosing melioidosis and assessing treatment outcome, supporting further validation in larger studies.
- The following article is Open accessDirect sampling of the peripheral lung identifies lung-derived volatile organic compounds detectable in exhaled breath: a feasibility study
Renelle Myers et al 2026 J. Breath Res. 20 036009
View article, Direct sampling of the peripheral lung identifies lung-derived volatile organic compounds detectable in exhaled breath: a feasibility studyPDF, Direct sampling of the peripheral lung identifies lung-derived volatile organic compounds detectable in exhaled breath: a feasibility studyExhaled breath (EB) testing holds potential for non-invasive screening and early detection of lung cancer. Development of such a test requires knowledge of volatile organic compounds (VOCs) originating in the lung microenvironment, rather than exogenous sources or non-lung endogenous sources such as the GI tract and oral cavity. Direct evidence linking peripheral lung-derived VOCs to EB is lacking. The peripheral lung air (⩾4th generation airways) of thirty-five participants (9 lung cancers; 26 controls) was sampled during bronchoscopy using micro-thermal desorption-gas chromatography-ion mobility spectrometry (µTD-GC-IMS) for direct on-site analysis and was compared to EB obtained immediately prior. Data processing included signal-normalized background subtraction to evaluate which VOCs originate in the peripheral lung and comparison to EB. Forty-three IMS clusters (features) were determined to originate from the lung microenvironment. All forty-three lung-originating features were detected in EB. Twenty-four out of forty-three features had higher median signal in either the EB or peripheral lung air compared to the environmental background. Some features had higher signal in EB compared to peripheral lung air, while others showed the reverse trend. Direct analysis of peripheral lung air, proximal to the tumour, using µTD-GC-IMS was clinically feasible. These findings help address a key translational barrier in breath-based respiratory biomarker development and support the feasibility of non-invasive approaches for lung cancer screening grounded in lung-specific VOC biology, and will inform larger clinical trials directed at breath biomarker discovery.
- The following article is Open accessSweet interference: oral fermentation volatile confounders in exhaled breath revealed by minimal glucose exposure
Anesu Chawaguta et al 2026 J. Breath Res.
View article, Sweet interference: oral fermentation volatile confounders in exhaled breath revealed by minimal glucose exposurePDF, Sweet interference: oral fermentation volatile confounders in exhaled breath revealed by minimal glucose exposureVolatile organic compounds (VOCs) in human breath have been explored as non-invasive
biomarkers for disease, including respiratory infections and cancer, yet very few breath tests have reached clinical validation and regulatory approval. A major barrier is the difficulty of identifying and controlling confounding factors
that affect volatile exhaled breath composition. A critical and overlooked confounder is the
oral microbiome, which produces VOCs that can obscure the trace volatiles originating from
the lower airways. To investigate this, we conducted an intervention study on sixteen healthy
volunteers, using real-time breath analysis, which demonstrates that oral microbiota rapidly
alter exhaled VOC profiles following a low-dose (0.5 g) oral glucose administration. Acetoin
levels respond promptly to glucose, confirming its oral microbial origin. However, pathogenic
bacteria resulting from respiratory infections can also produce acetoin, underscoring the
challenge of distinguishing sources of breath VOCs. Similarly, other volatiles, such as acetic
acid and ethanol, are also influenced by small glucose doses, complicating their use as
biomarkers in non-targeted volatilomic studies. Recognizing the metabolic context of each
volatile is essential to distinguish infection signals from physiological background. Beyond
serving as a cautionary note for exhaled breath research, these results may encourage the oral
health and dentistry communities to adopt breathomics analytical tools for rapid chairside
diagnostics, transforming respiratory confounders into clinical opportunities for dental care.
- The following article is Open accessA novel approach to non-invasive lung cancer screening via exhaled breath analysis using proton transfer reaction time-of-flight mass spectrometry
Maribel Hernández-Camarillo et al 2026 J. Breath Res. 20 036008
View article, A novel approach to non-invasive lung cancer screening via exhaled breath analysis using proton transfer reaction time-of-flight mass spectrometryPDF, A novel approach to non-invasive lung cancer screening via exhaled breath analysis using proton transfer reaction time-of-flight mass spectrometryLung cancer (LC) remains a global public health problem. To minimize late diagnosis, new detection techniques are needed. The analysis of volatile organic compounds (VOCs) in human breath (the volatilome) represents a non-invasive alternative to current methods for the early detection of LC. In this study, VOCs were determined in the breath of individuals with LC (N = 22) and without LC (non-LC, N = 21) using proton transfer reaction time-of-flight mass spectrometry. Orthogonal partial least squares discriminant analysis and hierarchical cluster analysis were conducted on a subset of 54 VOC ions (out of 180). Twenty-one of the 54 VOC ions were detected in exhaled breath. CH4O3H+ and C8H7NH+ were found only in participants without cancer. Among the 19 common ions present in both cohorts, the intensities of 8 ions were statistically different. The LC/non-LC ratios were observed for C4H8O2H+, followed by C3H4OH+, C2H2OH+, C2H3ONH+, C3H4H+, C3H2H+, C4H8H+, and C6H8H+. Spearman correlation analysis could be used to differentiate metabolic processes or pathways between cohorts. Diagnostic ratio is a potential tool to classify individuals with or without LC. This study provides exploratory evidence for exhaled VOCs as potential LC biomarkers and positions them as a complement to current diagnostic pathways, with a potential role in supporting early triage and clinical decision-making.
- The following article is Open accessThe oral cavity as a bioreactor in halitosis
Konstantinos Marinis et al 2026 J. Breath Res.
View article, The oral cavity as a bioreactor in halitosisPDF, The oral cavity as a bioreactor in halitosisHalitosis is a prevalent yet often underestimated clinical condition with multifactorial etiology, predominantly arising from intra-oral sources such as periodontal disease, tongue coating and xerostomia. Central to its pathogenesis is the microbial degradation of sulfur-containing substrates, which lead to the production of volatile sulfur compounds and other volatile organic compounds responsible for the characteristic odor. These metabolites are produced by proteolytic anaerobes inhabiting the tongue dorsum, periodontal pockets as well as the dental plaque and predominantly exist as structured biofilms. This review examines halitosis through a systems-based lens, conceptualizing the oral cavity as a dynamic bioreactor governed by microbial consortia and their metabolic pathways, mass transport, enzymatic kinetics, as well as growth conditions attributed to microenvironmental factors. Modeling approaches are required to elucidate the intricate dynamics within oral biofilms, including the heterogeneous structural organization and the fundamental transport and metabolic processes occurring at the biofilm-bulk fluid interface and within the biofilm matrix. These interfacial processes, in turn, regulate the flux of volatile compounds into the oral air. Furthermore, associations between halitosis and dental pathologies, including gingivitis, periodontitis, and periodontal abscesses, are explored through microbial dysbiosis. The review also addresses contemporary management strategies including mechanical debridement, antimicrobial agents and probiotics. Understanding the biochemical, microbial and reactor-like behavior of the oral cavity is critical for the effective diagnosis, monitoring and treatment of halitosis in clinical and research settings.
- The following article is Open accessAnalysis of fetal DNA in biological samples derived from maternal exhaled breath
Erkam Dolapci et al 2026 J. Breath Res. 20 036007
View article, Analysis of fetal DNA in biological samples derived from maternal exhaled breathPDF, Analysis of fetal DNA in biological samples derived from maternal exhaled breathObjective. Detection of cell-free fetal DNA (cffDNA) in maternal plasma has paved the way for non-invasive prenatal testing. The ability to detect cffDNA in various body fluids has increased interest in alternative sampling methods. Exhaled breath condensate (EBC) is a non-invasive specimen that allows analysis of genetic materials such as DNA and RNA. This study aimed to investigate the presence of fetal DNA in EBC samples from pregnant women. Materials And Methods. Thirty pregnant women carrying male fetuses as confirmed by routine ultrasonography were included in the study. EBC samples were collected, and DNA was extracted. The presence of the SRY gene was analyzed using digital droplet PCR. Results. The mean maternal age was 30.1 years, mean gestational age was 37 weeks, and mean DNA concentration was 17 ng µl−1. The SRY gene was detected in 11–30 samples (36.6%). All newborns were phenotypically male. Conclusion. This study demonstrates the detectability of fetal DNA in EBC samples from pregnant women and supports the feasibility of EBC as a novel non-invasive sampling matrix for prenatal genetic analysis. Although further methodological optimization is required, these findings highlight the potential of EBC as an alternative source of fetal genetic material for future prenatal testing applications.
- The following article is Open accessFrom dysbiotic gut to malodorous mouth: targeting microbial metabolism for gastrointestinal type halitosis
Xin Liang et al 2026 J. Breath Res. 20 034003
View article, From dysbiotic gut to malodorous mouth: targeting microbial metabolism for gastrointestinal type halitosisPDF, From dysbiotic gut to malodorous mouth: targeting microbial metabolism for gastrointestinal type halitosisThis article reviews the microbiological mechanisms of halitosis, the oral-gut axis, the role of the gut microbiome, related metabolic pathways, and their associations with gastrointestinal diseases, and explores intervention strategies based on microbial regulation. Halitosis is primarily caused by volatile sulfur compounds produced by oral microorganisms, especially gram-negative anaerobic bacteria, and volatile organic compounds in most extraoral etiologies. Studies have found that intestinal microbial dysregulation can affect the composition of oral flora through the oral-gut axis and aggravate bad breath. Gastrointestinal diseases, such as gastroesophageal reflux disease, Helicobacter pylori infection, ulcerative colitis and irritable bowel syndrome can directly or indirectly promote the occurrence of bad breath by changing the intestinal microenvironment and microbial metabolic pathways, such as protein spoilage or short-chain fatty acids imbalance, etc. For microbial interventions, traditional Chinese medicine can not only systemically regulate the oral-gut axis balance, but also effectively alleviate bad breath by targeting sterilization and inhibiting the metabolic activity of pathogenic bacteria. This review focuses on elucidating the complex links between halitosis and the gut microbiome, its metabolic pathways, and gastrointestinal diseases, emphasizing the key role of microbial metabolites in pathological mechanisms. It reveals the importance of the oral-gut axis in systemic health and provides a rationale for developing personalized halitosis management strategies based on microbiome regulation.
- The following article is Open accessMultifactorial assessment of halitosis in systemically and orally healthy orthodontic patients: airway dimensions, breathing pattern, and comparison with a portable breath analyzer
İsmail Ongun et al 2026 J. Breath Res. 20 036006
View article, Multifactorial assessment of halitosis in systemically and orally healthy orthodontic patients: airway dimensions, breathing pattern, and comparison with a portable breath analyzerPDF, Multifactorial assessment of halitosis in systemically and orally healthy orthodontic patients: airway dimensions, breathing pattern, and comparison with a portable breath analyzerHalitosis is a multifactorial condition influenced by airway-related factors and breathing patterns. This study aimed to evaluate the relationship between airway dimensions, craniofacial morphology, and breathing type with halitosis in orthodontic patients. In addition, the agreement between the portable breath analyzer and the organoleptic method, as well as the role of self-reported and physiological halitosis, was investigated. This cross-sectional study included 113 systemically and orally healthy orthodontic patients. Lateral cephalometric radiographs were used to assess the sagittal and vertical skeletal patterns and pharyngeal airway dimensions. Halitosis was evaluated using an organoleptic method as the reference standard and a portable breath analysis device for comparison. Oral hygiene habits, breathing type, and perception of halitosis were recorded using a structured questionnaire. Statistical analyses included appropriate parametric and nonparametric tests as well as multivariate logistic regression. Agreement was assessed using Cohen’s kappa coefficient. The overall prevalence of halitosis was 8.9% based on organoleptic assessment. Tooth brushing frequency (p = 0.041) and oral dryness (p = 0.004) were significantly associated with halitosis, whereas airway dimensions, skeletal patterns, and breathing types were not (p > 0.05). Physiological halitosis (p = 0.003) and oral dryness (p = 0.047) were significant predictors of self-reported halitosis. The agreement between the self-reported and objective measurements was weak (κ = 0.264; p < 0.001). A statistically significant and substantial level of agreement was observed between the portable device and the organoleptic assessment (κ = 0.698). Airway-related parameters were not identified as significant determinants of halitosis. Within the limitations of this study, halitosis was more closely associated with self-reported oral dryness and tooth-brushing frequency than with airway morphology. Portable breath analyzers may serve as practical adjunctive tools for clinical assessments when used under standardized conditions.
- The following article is Open accessWelding activities: is EBC a reliable indicator for assessing metal exposure or early biological effects? A systematic review
Veruscka Leso et al 2026 J. Breath Res. 20 034001
View article, Welding activities: is EBC a reliable indicator for assessing metal exposure or early biological effects? A systematic reviewPDF, Welding activities: is EBC a reliable indicator for assessing metal exposure or early biological effects? A systematic reviewWelding processes generate complex aerosols containing fine and ultrafine particulate matter, metal fumes, and gaseous by-products that may pose significant respiratory risks for exposed workers. Exhaled breath condensate (EBC) has emerged as a promising non-invasive matrix for human biomonitoring, offering the opportunity to assess exposure directly at the pulmonary target site and to evaluate early biological responses. This study systematically reviewed the scientific literature available in PubMed, Scopus, and ISI Web of Science to examine the role of EBC in exposure and effect biomonitoring among welders. Sixteen studies met the inclusion criteria. Overall, the evidence indicates that EBC is a suitable matrix for assessing occupational exposure in welding activities. Several studies reported increased concentrations of metals-including Manganese, Nickel, Iron, and Chromium in welders compared to unexposed controls, as well as higher post‐shift levels compared with pre‐shift samples across the workweek. Associations between cumulative exposure to inhalable dust and metal concentrations in EBC were also observed, even at low exposure levels. EBC has additionally shown potential for detecting early-effect biomarkers, such as indicators of oxidative stress, lipid peroxidation, protein and nucleic acid oxidation, and inflammatory mediators. These findings provide insight into biochemical alterations occurring in the airway lining fluid of welders. Despite encouraging findings, key methodological issues persist. The lack of standardized protocols for EBC collection, storage, and analysis hampers comparability across studies. Indeed, further research should elucidate EBC production and dilution kinetics and clarify metal toxicokinetics to fully establish EBC as a reliable biomonitoring matrix for occupational health research and practice.
- The following article is Open accessAge differences in overnight breath hydrogen dynamics and their association with sleep physiology
Naoya Okumura et al 2026 J. Breath Res. 20 036003
View article, Age differences in overnight breath hydrogen dynamics and their association with sleep physiologyPDF, Age differences in overnight breath hydrogen dynamics and their association with sleep physiologyOxidative stress increases with aging and may influence both sleep physiology and gut microbial activity. Molecular hydrogen, produced by intestinal fermentation, acts as an endogenous antioxidant and can be measured noninvasively in exhaled breath. However, age- and sex-related differences in nocturnal changes of breath hydrogen remain unclear. We analyzed breath hydrogen and methane levels in 166 healthy adults aged 20–85 years. Participants self-collected end-alveolar breath samples at home before sleep and immediately after waking. Breath hydrogen and methane levels were determined by gas chromatography. The older group (n = 91) showed significantly lower breath hydrogen levels after waking compared with the non-older group (n = 75), despite no differences before sleep. No significant sex-related differences were observed. The older group also reported more frequent nocturnal awakenings. These findings suggest that age-related changes in hydrogen dynamics may be associated with sleep-related physiological processes. The overnight change in breath hydrogen was significantly greater in the older group compared with the non-older group, indicating a larger overnight reduction in hydrogen levels in older adults. No significant differences in breath methane levels were observed between groups. Age-related alterations in gut microbiota, gastrointestinal motility, and redox balance may contribute to reduced morning hydrogen levels. Breath hydrogen measurement represents a simple, noninvasive biomarker for assessing physiological changes associated with aging and sleep.
- The human volatilome: volatile organic compounds (VOCs) in exhaled breath, skin emanations, urine, feces and saliva
Anton Amann et al 2014 J. Breath Res. 8 034001
View article, The human volatilome: volatile organic compounds (VOCs) in exhaled breath, skin emanations, urine, feces and salivaPDF, The human volatilome: volatile organic compounds (VOCs) in exhaled breath, skin emanations, urine, feces and salivaBreath analysis is a young field of research with its roots in antiquity. Antoine Lavoisier discovered carbon dioxide in exhaled breath during the period 1777–1783, Wilhelm (Vilém) Petters discovered acetone in breath in 1857 and Johannes Müller reported the first quantitative measurements of acetone in 1898. A recent review reported 1765 volatile compounds appearing in exhaled breath, skin emanations, urine, saliva, human breast milk, blood and feces. For a large number of compounds, real-time analysis of exhaled breath or skin emanations has been performed, e.g., during exertion of effort on a stationary bicycle or during sleep. Volatile compounds in exhaled breath, which record historical exposure, are called the ‘exposome’. Changes in biogenic volatile organic compound concentrations can be used to mirror metabolic or (patho)physiological processes in the whole body or blood concentrations of drugs (e.g. propofol) in clinical settings—even during artificial ventilation or during surgery. Also compounds released by bacterial strains like Pseudomonas aeruginosa or Streptococcus pneumonia could be very interesting. Methyl methacrylate (CAS 80–62–6), for example, was observed in the headspace of Streptococcus pneumonia in concentrations up to 1420 ppb. Fecal volatiles have been implicated in differentiating certain infectious bowel diseases such as Clostridium difficile, Campylobacter, Salmonella and Cholera. They have also been used to differentiate other non-infectious conditions such as irritable bowel syndrome and inflammatory bowel disease. In addition, alterations in urine volatiles have been used to detect urinary tract infections, bladder, prostate and other cancers. Peroxidation of lipids and other biomolecules by reactive oxygen species produce volatile compounds like ethane and 1-pentane. Noninvasive detection and therapeutic monitoring of oxidative stress would be highly desirable in autoimmunological, neurological, inflammatory diseases and cancer, but also during surgery and in intensive care units. The investigation of cell cultures opens up new possibilities for elucidation of the biochemical background of volatile compounds. In future studies, combined investigations of a particular compound with regard to human matrices such as breath, urine, saliva and cell culture investigations will lead to novel scientific progress in the field.
- A review of the volatiles from the healthy human body
B de Lacy Costello et al 2014 J. Breath Res. 8 014001
View article, A review of the volatiles from the healthy human bodyPDF, A review of the volatiles from the healthy human bodyA compendium of all the volatile organic compounds (VOCs) emanating from the human body (the volatolome) is for the first time reported. 1840 VOCs have been assigned from breath (872), saliva (359), blood (154), milk (256), skin secretions (532) urine (279), and faeces (381) in apparently healthy individuals. Compounds were assigned CAS registry numbers and named according to a common convention where possible. The compounds have been grouped into tables according to their chemical class or functionality to permit easy comparison. Some clear differences are observed, for instance, a lack of esters in urine with a high number in faeces. Careful use of the database is needed. The numbers may not be a true reflection of the actual VOCs present from each bodily excretion. The lack of a compound could be due to the techniques used or reflect the intensity of effort e.g. there are few publications on VOCs from blood compared to a large number on VOCs in breath. The large number of volatiles reported from skin is partly due to the methodologies used, e.g. collecting excretions on glass beads and then heating to desorb VOCs. All compounds have been included as reported (unless there was a clear discrepancy between name and chemical structure), but there may be some mistaken assignations arising from the original publications, particularly for isomers. It is the authors' intention that this database will not only be a useful database of VOCs listed in the literature, but will stimulate further study of VOCs from healthy individuals. Establishing a list of volatiles emanating from healthy individuals and increased understanding of VOC metabolic pathways is an important step for differentiating between diseases using VOCs.
- The physics of human breathing: flow, timing, volume, and pressure parameters for normal, on-demand, and ventilator respiration
Joachim D Pleil et al 2021 J. Breath Res. 15 042002
View article, The physics of human breathing: flow, timing, volume, and pressure parameters for normal, on-demand, and ventilator respirationPDF, The physics of human breathing: flow, timing, volume, and pressure parameters for normal, on-demand, and ventilator respirationNormal breathing for healthy humans is taken for granted; it occurs without conscious effort using ambient (1-atmosphere) pressure with 21% oxygen (O2) concentration. The body automatically adjusts for stress, exercise, altitude, and mild disease by increasing the volume and frequency of breathing. Longer term adaptations for exercise and altitude include increases in red blood cell counts and higher concentrations of capillaries in muscle tissue. When more challenging external environmental conditions or pulmonary illnesses exceed the capability for these adaptations, the human system requires technology to maintain sufficient ventilation to preserve life. On the environmental side there are two conditions to be addressed: toxicity of the surrounding atmosphere and changes in external pressure and O2 concentration. On the medical side, mechanisms for assisting breathing include O2 supplementation at ambient pressure, positive pressure/flow without additional O2, or a combination of both. This overview describes the various technologies applied to maintaining a safe breathing environment. Topics for environmental intervention include filter-based and flowing air-supply masks for toxic environments (occupational and laboratory protection), and on-demand gas supply systems for firefighters, self-contained underwater breathing apparatus divers, and altitude (high performance aircraft, spacecraft) applications. The topics for medical intervention include nasal cannula, continuous positive airway pressure, and medical ventilators. The primary purpose of this article is to provide a basic understanding of normal human breathing and the adaptation of breathing in different environments using available technologies.
- A literature survey of all volatiles from healthy human breath and bodily fluids: the human volatilome
Natalia Drabińska et al 2021 J. Breath Res. 15 034001
View article, A literature survey of all volatiles from healthy human breath and bodily fluids: the human volatilomePDF, A literature survey of all volatiles from healthy human breath and bodily fluids: the human volatilomeThis paper comprises an updated version of the 2014 review which reported 1846 volatile organic compounds (VOCs) identified from healthy humans. In total over 900 additional VOCs have been reported since the 2014 review and the VOCs from semen have been added. The numbers of VOCs found in breath and the other bodily fluids are: blood 379, breath 1488, faeces 443, milk 290, saliva 549, semen 196, skin 623 and urine 444. Compounds were assigned CAS registry numbers and named according to a common convention where possible. The compounds have been included in a single table with the source reference(s) for each VOC, an update on our 2014 paper. VOCs have also been grouped into tables according to their chemical class or functionality to permit easy comparison. Careful use of the database is needed, as a number of the identified VOCs only have level 2—putative assignment, and only a small fraction of the reported VOCs have been validated by standards. Some clear differences are observed, for instance, a lack of esters in urine with a high number in faeces and breath. However, the lack of compounds from matrices such a semen and milk compared to breath for example could be due to the techniques used or reflect the intensity of effort e.g. there are few publications on VOCs from milk and semen compared to a large number for breath. The large number of volatiles reported from skin is partly due to the methodologies used, e.g. by collecting skin sebum (with dissolved VOCs and semi VOCs) onto glass beads or cotton pads and then heating to a high temperature to desorb VOCs. All compounds have been included as reported (unless there was a clear discrepancy between name and chemical structure), but there may be some mistaken assignations arising from the original publications, particularly for isomers. It is the authors’ intention that this work will not only be a useful database of VOCs listed in the literature but will stimulate further study of VOCs from healthy individuals; for example more work is required to confirm the identification of these VOCs adhering to the principles outlined in the metabolomics standards initiative. Establishing a list of volatiles emanating from healthy individuals and increased understanding of VOC metabolic pathways is an important step for differentiating between diseases using VOCs.
- Dependence of exhaled breath composition on exogenous factors, smoking habits and exposure to air pollutants
W Filipiak et al 2012 J. Breath Res. 6 036008
View article, Dependence of exhaled breath composition on exogenous factors, smoking habits and exposure to air pollutantsPDF, Dependence of exhaled breath composition on exogenous factors, smoking habits and exposure to air pollutantsNon-invasive disease monitoring on the basis of volatile breath markers is a very attractive but challenging task. Several hundreds of compounds have been detected in exhaled air using modern analytical techniques (e.g. proton-transfer reaction mass spectrometry, gas chromatography-mass spectrometry) and have even been linked to various diseases. However, the biochemical background for most of compounds detected in breath samples has not been elucidated; therefore, the obtained results should be interpreted with care to avoid false correlations. The major aim of this study was to assess the effects of smoking on the composition of exhaled breath. Additionally, the potential origin of breath volatile organic compounds (VOCs) is discussed focusing on diet, environmental exposure and biological pathways based on other's studies. Profiles of VOCs detected in exhaled breath and inspired air samples of 115 subjects with addition of urine headspace derived from 50 volunteers are presented. Samples were analyzed with GC-MS after preconcentration on multibed sorption tubes in case of breath samples and solid phase micro-extraction (SPME) in the case of urine samples. Altogether 266 compounds were found in exhaled breath of at least 10% of the volunteers. From these, 162 compounds were identified by spectral library match and retention time (based on reference standards). It is shown that the composition of exhaled breath is considerably influenced by exposure to pollution and indoor-air contaminants and particularly by smoking. More than 80 organic compounds were found to be significantly related to smoking, the largest group comprising unsaturated hydrocarbons (29 dienes, 27 alkenes and 3 alkynes). On the basis of the presented results, we suggest that for the future understanding of breath data it will be necessary to carefully investigate the potential biological origin of volatiles, e.g., by means of analysis of tissues, isolated cell lines or other body fluids. In particular, VOCs linked to smoking habit or being the results of human exposure should be considered with care for clinical diagnosis since small changes in their concentration profiles (typically in the pptv–ppbv range) revealing that the outbreak of certain disease might be hampered by already high background.
- Factors that influence the volatile organic compound content in human breath
L Blanchet et al 2017 J. Breath Res. 11 016013
View article, Factors that influence the volatile organic compound content in human breathPDF, Factors that influence the volatile organic compound content in human breathBackground. Thousands of endogenous and exogenous volatile organic compounds (VOCs) are excreted in each breath. Inflammatory and deviant metabolic processes affect the level of endogeneous VOCs, which can serve as specific biomarkers for clinical diagnosis and disease monitoring. Important issues that still need to be tackled are related to potential confounding factors like gender and age and endogenous and exogenous factors, like f.i. smoking. Methods. The aim of this study was to systematically access the effect of endogenous and exogenous factors on VOC composition of exhaled breath. In the current study breath samples from 1417 adult participants from the LifeLines cohort, a general population cohort in the Netherlands, were collected and the total content of VOCs was measured using gas chromatography-time-of-flight-mass spectrometry. Breath samples were collected in Groningen and transferred to carbon tubes immediately. These samples were then shipped to Maastricht and measured in batches. VOCs profiles were correlated to 14 relevant characteristics of all participants including age, BMI, smoking and blood cell counts and metabolic parameters as well as to 16 classes of medications. Results. VOCs profiles were shown to be significantly influenced by smoking behavior and to a lesser extent by age, BMI and gender. These factors need to be controlled for in breath analysis studies. We found no evidence whatsoever in this 1417 subjects’ cohort that white blood cell counts, cholesterol or triglycerides levels have an influence on the VOC profile. Thus they may not have to be controlled for in exhaled breath studies. Conclusion. The large cohort of volunteers used here represents a unique opportunity to gauge the factors influencing VOCs profiles in a general population i.e. the most clinically relevant population. Classical clinical parameters and smoking habits clearly influence breath content and should therefore be accounted for in future clinical studies involving breath analysis.
- Exhaled breath condensate (EBC) in respiratory diseases: recent advances and future perspectives in the age of omic sciences
Mauro Maniscalco et al 2024 J. Breath Res. 18 045001
View article, Exhaled breath condensate (EBC) in respiratory diseases: recent advances and future perspectives in the age of omic sciencesPDF, Exhaled breath condensate (EBC) in respiratory diseases: recent advances and future perspectives in the age of omic sciencesExhaled breath condensate (EBC) is used as a promising noninvasive diagnostic tool in the field of respiratory medicine. EBC is achieved by cooling exhaled air, which contains aerosolized particles and volatile compounds present in the breath. This method provides useful information on the biochemical and inflammatory state of the airways. In respiratory diseases such as asthma, chronic obstructive pulmonary disease and cystic fibrosis, EBC analysis can reveal elevated levels of biomarkers such as hydrogen peroxide, nitric oxide and various cytokines, which correlate with oxidative stress and inflammation. Furthermore, the presence of certain volatile organic compounds in EBC has been linked to specific respiratory conditions, potentially serving as disease-specific fingerprints. The noninvasive nature of EBC sampling makes it particularly useful for repeated measures and for use in vulnerable populations, including children and the elderly. Despite its potential, the standardization of collection methods, analytical techniques and interpretation of results currently limits its use in clinical practice. Nonetheless, EBC holds significant promise for improving the diagnosis, monitoring and therapy of respiratory diseases. In this tutorial we will present the latest advances in EBC research in airway diseases and future prospects for clinical applications of EBC analysis, including the application of the Omic sciences for its analysis.
- The following article is Open accessVolatile compounds in human breath: critical review and meta-analysis
Theo Issitt et al 2022 J. Breath Res. 16 024001
View article, Volatile compounds in human breath: critical review and meta-analysisPDF, Volatile compounds in human breath: critical review and meta-analysisVolatile compounds contained in human breath reflect the inner workings of the body. A large number of studies have been published that link individual components of breath to disease, but diagnostic applications remain limited, in part due to inconsistent and conflicting identification of breath biomarkers. New approaches are therefore required to identify effective biomarker targets. Here, volatile organic compounds have been identified in the literature from four metabolically and physiologically distinct diseases and grouped into chemical functional groups (e.g. methylated hydrocarbons or aldehydes; based on known metabolic and enzymatic pathways) to support biomarker discovery and provide new insight on existing data. Using this functional grouping approach, principal component analysis doubled explanatory capacity from 19.1% to 38% relative to single individual compound approaches. Random forest and linear discriminant analysis reveal 93% classification accuracy for cancer. This review and meta-analysis provides insight for future research design by identifying volatile functional groups associated with disease. By incorporating our understanding of the complexities of the human body, along with accounting for variability in methodological and analytical approaches, this work demonstrates that a suite of targeted, functional volatile biomarkers, rather than individual biomarker compounds, will improve accuracy and success in diagnostic research and application.
- A mechanistic study and review of volatile products from peroxidation of unsaturated fatty acids: an aid to understanding the origins of volatile organic compounds from the human body
Norman Ratcliffe et al 2020 J. Breath Res. 14 034001
View article, A mechanistic study and review of volatile products from peroxidation of unsaturated fatty acids: an aid to understanding the origins of volatile organic compounds from the human bodyPDF, A mechanistic study and review of volatile products from peroxidation of unsaturated fatty acids: an aid to understanding the origins of volatile organic compounds from the human bodyThe assessment of volatile compounds (VOCs) for disease diagnosis is a growing area of research. There is a need to provide hard evidence i.e. biochemical routes, to justify putative VOC biomarkers, as in many cases this remains uncertain, which weakens their authenticity. Recently reports of volatile hydrocarbons and or aldehydes in bodily fluids and breath have been attributed to oxidative stress, although as discussed here, fewer compounds have been reported than expected from a mechanistic examination. Oxidative stress can result from many disease states which produce inflammation, and a better understanding of the interconnection between oxidative stress and the release of VOCs from target diseased and healthy organs could greatly help diagnoses. It is generally considered that oxidation of unsaturated fatty acids are a major source of these VOCs. An investigation listing the many possible volatile oxidation products has not been undertaken. This is described here using a mechanistic analysis (based on the literature) of the compounds derived from molecular cleavage and the results compared with a recent review of all the VOCs emanating from the human body, which satisfactorily explains the presence of at least 100 VOCs. Six important unsaturated fatty acids, oleic, palmitoleic, linoleic, linolenic, arachidonic, and cervonic acids have been shown to be capable of producing up to 18 n+6 unique breakdown products (where n = the number of alkene double bonds in the fatty acid hydrocarbon chain), in total 299 compounds. In many cases these have not been reported. We suggest several reasons for this: these VOCs have not been expected, so researchers are not looking for them and importantly some are not present in the mass spectral libraries, or they are too low a concentration to have been detected, or are not present. Furthermore a theoretical explanation for the origins of branched aldehydes and other compounds arising from bacterial oxidative metabolism of unsaturated fatty acids are described.
- Is breath acetone a biomarker of diabetes? A historical review on breath acetone measurements
Zhennan Wang and Chuji Wang 2013 J. Breath Res. 7 037109
View article, Is breath acetone a biomarker of diabetes? A historical review on breath acetone measurementsPDF, Is breath acetone a biomarker of diabetes? A historical review on breath acetone measurementsSince the ancient discovery of the ‘sweet odor’ in human breath gas, pursuits of the breath analysis-based disease diagnostics have never stopped. Actually, the ‘smell’ of the breath, as one of three key disease diagnostic techniques, has been used in Eastern-Medicine for more than three thousand years. With advancement of measuring technologies in sensitivity and selectivity, more specific breath gas species have been identified and established as a biomarker of a particular disease. Acetone is one of the breath gases and its concentration in exhaled breath can now be determined with high accuracy using various techniques and methods. With the worldwide prevalence of diabetes that is typically diagnosed through blood testing, human desire to achieve non-blood based diabetic diagnostics and monitoring has never been quenched. Questions, such as is breath acetone a biomarker of diabetes and how is the breath acetone related to the blood glucose (BG) level (the golden criterion currently used in clinic for diabetes diagnostic, monitoring, and management), remain to be answered. A majority of current research efforts in breath acetone measurements and its technology developments focus on addressing the first question. The effort to tackle the second question has begun recently. The earliest breath acetone measurement in clearly defined diabetic patients was reported more than 60 years ago. For more than a half-century, as reviewed in this paper, there have been more than 41 independent studies of breath acetone using various techniques and methods, and more than 3211 human subjects, including 1581 healthy people, 242 Type 1 diabetic patients, 384 Type 2 diabetic patients, 174 unspecified diabetic patients, and 830 non-diabetic patients or healthy subjects who are under various physiological conditions, have been used in the studies. The results of the breath acetone measurements collected in this review support that many conditions might cause changes to breath acetone concentrations; however, the results from the six independent studies using clearly-defined Type 1 and Type 2 diabetic patients unanimously support that an elevated mean breath acetone concentration exists in Type 1 diabetes. Note that there is some overlap between the ranges of breath acetone concentration in individual T1D patients and healthy subjects; this reminds one to be careful when using an acetone breath test on T1D diagnostics. Comparatively, it is too early to draw a general conclusion on the relationship between a breath acetone level and a BG level from the very limited data in the literature.
Journal resources
Journal information
- 2007-present
Journal of Breath Research
doi: 10.1088/issn.1752-7163
Online ISSN: 1752-7163
Print ISSN: 1752-7155