Influence of puff topographies on e-liquid heating temperature, emission characteristics and modeled lung deposition of Puff Bar™

Abstract

Puff Bar™, one of the latest designs of e-cigarettes, heats a mixture of liquid using a battery-powered coil at certain temperatures to emit aerosol. This study presents a mass-based characterization of emissions from seven flavors of Puff Bar™ devices by aerosolizing with three puff topographies [(puff volume: 55 < 65 < 75-mL) within 4-seconds at 30-seconds interval]. We evaluated the effects of puff topographies on heating temperatures; characterized particles using a cascade impactor; and measured volatile carbonyl compounds (VCCs). Modeled dosimetry and calculated mass median aerodynamic diameters (MMADs) were used to estimate regional, total respiratory deposition of the inhaled aerosol and exhaled fractions that could pose secondhand exposure risk. Temperatures of Puff Bar™ e-liquids increased with increasing puff volumes: 55 mL (116.6 °C), 65 mL (128.3 °C), and 75 mL (168.9 °C). Flavor types significantly influenced MMADs, total mass of particles, and VCCs (µg/puff: 2.15-2.30) in Puff Bar™ emissions (p < 0.05). Increasing puff volume (mL:55 < 65 < 75) significantly increased total mass (mg/puff: 4.6 < 5.6 < 6.2) of particles without substantially changing MMADs (∼1µm:1.02 ∼ 0.99 ∼ 0.98). Aerosol emissions were estimated to deposit in the pulmonary region of e-cigarette user (41–44%), which could have toxicological importance. More than 2/3 (67–77%) of inhaled particles were estimated to be exhaled by users, which could affect bystanders. The VCCs measured contained carcinogens—formaldehyde (29.6%) and acetaldehyde (16.4%)—as well as respiratory irritants: acetone (23.9%), isovaleraldehyde (14.5%), and acrolein (4.9%). As Puff Bar™ emissions contain respirable particles and harmful chemicals, efforts should be made to minimize exposures, especially in indoor settings where people (including vulnerable populations) spend most of their life-time.

Copyright © 2023 American Association for Aerosol Research

Graphic Abstract

EDITOR:

• Darragh Murnane

Acknowledgment

The authors would like to thank Clifford Watson and Alyson Fortner for technical review of this manuscript prior to submission to the journal.

Disclosure statement

The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. Mention of any company or product does not constitute endorsement by the U.S. Government, National Institute for Occupational Safety and Health, or Centers for Disease Control and Prevention. This work was supported by NIOSH intramural research funds. All web addresses referenced in this document were accessible as of the publication date.

Data availability statement

Anonymized data and original contributions presented in the research study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author/s.

Additional information

Funding

This study was supported by CDC/NIOSH intramural research funds.