Full-scale determination of essential oil diffusion: Impact on indoor air quality

Abstract

Essential oils have attracted increasing interest, as they inhibit the metabolic functions of microorganisms. Essential oils are claimed to improve indoor air quality through passive remediation and purifying activities. However, the impact of diffused essential oils on indoor air quality has not been clearly established from a VOC point of view. This study aims to assess the emissions produced by terpene molecules in tea tree essential oil by employing two types of widespread diffusers under real conditions using a full-scale experimental room (40 m3). The emissions generated by terpenoid volatile organic compounds (TerVOCs) are different depending on the type of diffuser. The relative contributions of individual terpenes in the gas phase vary throughout the diffusion process. The impact of tea tree essential oil diffusion on indoor air quality varies from 6 h to 51 days, depending on the diffusion device. Concentration levels can exceed European recommended exposure levels by more than one order of magnitude. Interestingly, the volume of the emission chamber directly impacts the emission dynamics of essential oil constituents. Small chambers may limit the volume of air to be contaminated and possibly impacts the magnitude of concentration gradients during diffusion. This work evidences the interest of using full-scale experimental facilities to determine accurate emission rates. A full-scale experimental methodology including data treatment is validated in this work. Through the proposed protocol, representative emission factors can be determined to assess exposure and perform indoor air modelling.