Estimation of the dose of electronic cigarette chemicals deposited in human airways through passive vaping.

Introduction:
This text discusses an innovative approach to estimate the deposited dose of electronic cigarette (e-cigarette) chemicals in the airways of passive vapers, or individuals who inhale e-cigarette aerosol unintentionally. The study uses the Mobile aerosol Lung Deposition apparatus (MaLDa) to conduct aerosol respiratory deposition experiments in real-life settings and generate real-time data. The methodology developed in this study has laid the groundwork for future research on exposure assessment and health risk analysis for passive vaping.

Key Points:

* The study proposes a new approach to estimate the dose of e-cigarette chemicals in human airways by integrating the respiratory deposition estimated by MaLDa with chemical analysis results.
* The MaLDa is used to estimate the respiratory deposition of ultrafine particles (UFPs) in the entire human airways, with the special feature of being transportable between laboratories and real-life settings.
* The study conducts chemical analyses based on e-cigarette aerosol instead of e-liquid, focusing on a selected set of e-cigarette chemicals that have been classified as irritants or proven to cause adverse health effects.
* The study examines whether the deposited dose is affected by the distance between active and passive vapers.
* The MaLDa is used to estimate the respiratory deposition of e-cigarette aerosol in a real-life setting at two distances, 2 meters and 4 meters, from an e-cigarette user.
* The study calculates the deposition fractions of e-cigarette aerosol in the head-to-tracheobronchial (TB) airway and the alveolar region using the MaLDa data.
* The chemical analysis is conducted using two different analytical techniques to gain the best sensitivity to detect nicotine and flavoring agents in the e-cigarette aerosol.
* The deposited dose (per hour) for e-cigarette aerosol, nicotine, and benzyl alcohol in the head-to-TB airway and the alveolar region is estimated using Eq. (3) and the size-dependent chemical constituent data.

Main Message:
The study highlights the potential health risks of passive vaping, especially with prolonged exposure and close proximity to active vapers. The methodology developed in this study has laid the groundwork for future research on exposure assessment and health risk analysis for passive vaping. The results suggest that the MaLDa approach can provide evidence-based recommendations to policymakers and the general public regarding the minimum distance between active and passive vapers. Therefore, it is crucial to regulate and control e-cigarette use in public spaces to protect passive vapers and prevent potential health risks.

Su WC, Lin Yh, Wong SW, Chen JY, Lee J, Buu a. Estimation of the dose of electronic cigarette chemicals deposited in human airways through passive vaping. Journal of exposure science & environmental epidemiology. 2021;31(6):1008-1016. doi:10.1038/s41370-021-00362-0