Simulation Modeling of air and Droplet Temperatures in the human Respiratory Tract for Inhaled Tobacco Products.

Introduction:
This article presents a study on the temperature evolution of inhaled puffs in the human respiratory tract during different puff inhalation events. The study aimed to improve dose predictions for tobacco product smoke and aerosols by accounting for changes in the physicochemical properties of constituents due to temperature variations.

Key Points:

* The study developed energy equations for the transport of the puff in the respiratory tract and solved them to find air and droplet temperatures throughout the respiratory tract during two puffing scenarios: direct inhalation of the puff into the lung with no pause in the oral cavity, and puff withdrawal, mouth hold, and puff delivery to the lung via inhalation of dilution air.
* The model predictions showed that temperature effects were most significant during puff withdrawal. Otherwise, the puff reached thermal equilibrium with the body.
* The study used a single respiratory tract geometry to study temperature evolution of inhaled air and droplets, obtaining a closed-form solution for representative temperature distributions in the respiratory tract.
* The temperature model can then be coupled with transport models to simulate the fate of inhaled tobacco products in the entire respiratory tract.
* The study's findings will improve predictions of deposition and uptake of puff constituents, thereby informing inhalation risk assessment from the use of electronic nicotine delivery systems (ENDS) and combusted cigarettes.

Main Message:
The study emphasizes the importance of accounting for temperature-dependent changes in the physicochemical properties of tobacco product constituents in respiratory tract dosimetry predictions. By improving dose predictions, regulatory agencies can make better-informed decisions regarding the safety and risk assessment of tobacco products, ultimately protecting public health.

asgharian B, Price O, Creel a, et al. Simulation Modeling of air and Droplet Temperatures in the human Respiratory Tract for Inhaled Tobacco Products. annals of biomedical engineering. 2023;51(4):741-750. doi:10.1007/s10439-022-03082-0