Volatile organic compound and particle emissions from the use of tea tree oil in essential oil diffusers

A pilot-scale simulation study of tea tree oil (TTO) airborne dispersion in a household setting was conducted to evaluate emissions of volatile organic compounds (VOCs), including terpenes ("TerVOCs"), and various particle size classes while using an ultrasonic diffuser ("Survey 1") and a heat diffuser ("Survey 2"). Of the VOCs evaluated, isopropyl alcohol and p-dichlorobenzene were detected in one or more surveys, and their measured concentrations were below relevant exposure limits. Total VOC levels were measured above background (approximately 200 to 300 ppb) by one to two orders of magnitude during Surveys 1 and 2, respectively. TerVOC levels collected during Survey 1 were below applicable exposure limits. Air concentrations of α-pinene, α-terpinene, α-terpinolene, γ-terpinene, and p-isopropyltoluene for samples collected during Survey 2, however, exceeded long-term derived no-effect levels (DNELs) for worker and/or general populations, and α-pinene measurements exceeded the long-term exposure limit established by the European Commission through the INDEX project. TerVOC concentrations detected during Survey 2 were generally an order of magnitude higher than samples collected during Survey 1. This study is the first peer-reviewed publication known to the authors to report data collected during essential oil diffuser operations in a residential setting in the United States.