Essential oils, asthma, thunderstorms, and plant gases: a prospective study of respiratory response to ambient biogenic volatile organic compounds (BVOCs)

Abstract

Purpose: Prevailing opinion is that wind-pollinated plants affect asthma negatively and that insect- pollinated ones do not. “Thunderstorm” asthma, too, is attributed to bursting grass pollens. Additional biogenic volatile organic compounds (BVOCs) are identified here. Essential oils’ BVOCs are inhaled from plants, oil diffusers, candles, room “fresheners”, perfumes, and hygiene products. Claims of BVOC “safety” for sensitive respiratory systems are questioned.

Methods: Fourteen volunteers, of mixed-age and gender, with seasonal asthma recorded peak expiratory flow (PEF) and 11 symptom scores. BVOCs were collected on Tenax tubes from ambient air in autumn and spring, as were live flower emissions, before and after a thunderstorm. Gas chromatography–mass spectrometry analysis identified frequently occurring BVOCs. Air spora, meteorological, outdoor air pollution variables, and BVOCs predict respiratory symptoms in univariate linear regression models, seasonally.

Results: Increased pinene, camphor, linalool, linalyl acetate, benzaldehyde, and benzoic acid predict respiratory symptoms, including reduced PEF, and increased nasal congestion; day length, atmospheric pressure and temperature predict symptoms in both seasons, differently; other variables predict a range of symptoms (0.0001≤p≤0.05). Thunder predicts different BVOC emissions in spring, compared to autumn (p≤0.05). An uncut Grevillea flower emitted linalool and hexenal before a storm; the latter is also emitted from cut grass. Increased nitrogen oxides and pinene in autumn may combine to form harmful oxidation products.

Conclusion: This research supports BVOCs as contributors to seasonal asthma and allergic rhinitis, and “thunderstorm” asthma. Pinene emissions from Myrtaceae species (Eucalyptus, Melaleuca, Leptospermum, Callistemon), Brassicaceae (canola), and conifers, worldwide, may induce respiratory inflammation and maintain it, by inhibiting eosinophilic apoptosis. Widely used essential oil products containing BVOCs, like linalool, are associated here with respiratory symptoms. Lagged responses suggest that users’ cognitive associations between exposure and response are unlikely, increasing potential for impaired health for vulnerable children.

Keywords:

• asthma
• allergic rhinitis
• BVOC
• terpenes
• Eucalyptus
• essential oils

View correction statement:

Essential Oils, Asthma, Thunderstorms, and Plant Gases: A Prospective Study of Respiratory Response to Ambient Biogenic Volatile Organic Compounds (BVOCs) [Corrigendum]

Acknowledgments

I sincerely thank all the volunteer participants, my supporters, the air and flower analysts and the Asthma Foundation of Queensland (now Asthma Australia) for funding the original research that provided data for this analysis. No funding was received for this new analysis of previously collected data. The National Research Centre for Environmental Toxicology, ENTOX provided a scholarship to the author for the preliminary stages of the original project; The Asthma Foundation of Queensland funded the original research and provided scholarships to the author; Griffith University provided equipment and supported the original project throughout. Funding sources had no role in the study design, data collection, data analysis, data interpretation, or writing the article.

Ethics approval and informed consent

Ethics approval was sought and obtained from the Griffith University Human Research Ethics Committee. All methods were performed in accordance with the relevant guidelines and regulations from Griffith University. Informed written consent was obtained from adults, and parents or guardians, and children/minors.

Disclosure

The author reports no conflicts of interest in this work.