Investigating short-term lung inflammation using exhaled breath VOCs from exposure to candles: a randomized controlled crossover study among young mild asthmatics

Clinical Snapshot

Key Findings

• P Value: Significant after Benjamini-Hochberg correction (specific p-values not provided)

• Effect Size: Clear PCA separation between baseline and 5-hour samples, particularly for candle B exposure

• Primary Outcome: Ten exhaled VOCs showed significant changes between baseline and 5-hour post-exposure, including increased aldehydes and decreased sulfur compounds

• Nnt Or Sensitivity: VOC signature capable of distinguishing exposed individuals, but sensitivity/specificity not quantified

• Confidence Interval: Not reported

Clinical Application

Requires specialised VOC analysis equipment and controlled exposure facilities, limiting clinical applicability Limited immediate relevance to Australian practice; potential future application for occupational health monitoring or air quality research through NHMRC-funded studies Young adults with mild asthma in research settings

Abstract

Lung inflammation is associated with a response to pollution or irritants and is reported to release volatile organic compounds (VOCs) in breath, that can be monitored non-invasively. An approach to studying short-term lung inflammation is exposure to environmental emissions. This study used brief exposure to PM₂.₅ emissions from two types of burning candles to evaluate potential differences in airway inflammation among mildly asthmatic individuals. The aim was to explore VOCs linked to lung inflammation by exposure to candle emissions; emissions from candle A, a newly developed candle with a smaller emission to the surroundings and candle B, a well-characterised commercially available candle. Seventeen non-smoking asthmatics (11 female) with a mean age of 21.9 years participated in a randomised controlled double-blind crossover study including two exposure sessions: i) air with candle A emissions (mean PM2.554.1µg m-3), and ii) air with candle B emissions (mean PM2.598.4µg m-3). Participants underwent two five-hour, double-blind exposure sessions in a controlled climate chamber, each involving emissions from one of two candle types. Exhaled breath was collected at baseline (0 h), immediately post-exposure (5 h), and the following morning (24 h). VOCs were analysed using both a targeted panel of 23 predefined compounds and an untargeted workflow, which yielded 21 breath-derived VOCs after ambient-blank filtering. Statistical comparisons used Wilcoxon signed-rank tests with Benjamini-Hochberg correction. Across both exposure sessions, ten exhaled VOCs showed significant changes between baseline and immediate post-exposure (5 h), including increases in several aldehydes and decreases in selected sulfur-containing compounds. These changes were not present at 24 h, where samples resembled baseline profiles. The ten VOCs were identified from a combined dataset of 23 targeted compounds and 21 untargeted breath-derived VOCs; only the untargeted analysis yielded significant findings after correction. PCA demonstrated clear separation between baseline and 5 h samples, particularly for candle B, for which 0 h, 5 h and 24 h samples formed distinct clusters. This candle-specific response produced a multi-VOC signature capable of distinguishing individuals immediately after exposure, suggesting that exhaled VOCs can reflect short-term airway inflammatory responses. The findings suggest that an emission-specific, exhaled breath, multi-VOC profile can detect individuals exposed to inflammation triggers, such as candles. This indicates that VOCs could serve as biomarkers for detecting short-term airway inflammation, as evidenced by the systematic difference in VOCs observed 5 h after exposure to candle B. This research contributes to the advancing field of VOC-based health monitoring and might affect public health implications.

References

1. 1.Laursen, K. R., Woodland, T., Schaber, C., Østergaard, K., Birch, O., O'Brien, B., Mead, D., Kjærgaard, S. K., Allsworth, M., Boyle, B., van Schooten, F. J., Smolinska, A., & Sigsgaard, T. (2026). Investigating short-term lung inflammation using exhaled breath VOCs from exposure to candles: a randomized controlled crossover study among young mild asthmatics. Journal of Breath Research. https://doi.org/10.1088/1752-7163/ae6687