Table 1.

Respiratory system research of electronic cigarette harms including the title, type of review, first author, reference number in the manuscript, journal and year, and a brief summary of the review’s significant findings (N = 26).

Title	Review Type	Authors/Ref No.	Journal/Year	Significance of Finding
“The Impact of E-Cigarette Exposure on Different Organ Systems: A Review of Recent Evidence and Future Perspectives.”	Narrative Review	Ali, N. et al. [8]	J. Hazard. Mater. 2023	“The summarized data in this review indicate that while e-cigs use causes less adverse effects on different organs compared to traditional cigs, its long-term exposure may lead to serious health effects.”
“Impact of Vaping on Respiratory Health.”	Narrative Review	Jonas, A. [9]	BMJ. 2022	This study reviews “the clinical manifestations of vaping related lung injury, including the EVALI outbreak, as well as the effects of chronic vaping on respiratory health and COVID-19 outcomes.”
“Association Between E-Cigarettes and Asthma in Adolescents: A Systematic Review and Meta-Analysis.”	Systematic Review	Li, X. et al. [10]	Am. J. Prev. Med. 2022	“This study systematically evaluated the potential association between E-cigarette use and asthma in adolescents.”
“The Rise of Electronic Nicotine Delivery Systems and the Emergence of Electronic-Cigarette-Driven Disease.”	Narrative Review	McAlinden, K.D. et al. [11]	Am. J. Physiol. Lung Cell. Mol. Physiol. 2020	“E-cigarette vapor is shown to affect numerous cellular processes, cellular metabolism, and cause DNA damage... E-cigarette use is associated with a higher risk of developing crippling lung conditions such as chronic obstructive pulmonary disease (COPD)….”
“Association of Electronic Cigarette Use with Respiratory Symptom Development among U.S. Young Adults.”	Narrative Review	Xie, W. et al. [12]	Am. J. Respir. Crit. Care Med. 2022	“In this nationally representative cohort of young adults, former and current e-cigarette use was associated with higher odds of developing wheezing-related respiratory symptoms, after accounting for cigarette smoking and other combustible tobacco product use.”
“E-Cigarette Use: Device Market, Study Design, and Emerging Evidence of Biological Consequences”	Narrative Review	Snoderly, H.T. et al. [13]	Int. J. Mol. Sci. 2021	“…current literature reports that electronic cigarette use is associated with both acute lung injury and subclinical dysfunction to the lung and vasculature that may result in pathology following chronic use. E-cigarettes can alter vascular dynamics, polarize innate immune populations towards a proinflammatory state, compromise barrier function in the pulmonary endothelium and epithelium, and promote pre-oncogenic phenomena.”
“Oral and Systemic Health Implications of Electronic Cigarette Usage as Compared to Conventional Tobacco Cigarettes: A Review of the Literature.”	Narrative Review	Abbott, A.J. et al. [15]	J. Dent. Hyg. 2023	“According to current research, e-cigarettes may induce less harm than traditional tobacco products, but e-cigarettes do not remove the carcinogenic and toxic risk that has been associated with conventional cigarettes. Further research is needed to make broad conclusions on the safety of e-cigarettes compared to conventional cigarettes and to nonusers.”
“Electronic Cigarette Use, Misuse, and Harm.”	Narrative Review	Kathuria H. [16]	Med. Clin. North Am. 2022	“Studies show that e-cigarette use can increase the risk to nicotine dependence and combustible tobacco use. Studies show an association between e-cigarette use and pulmonary disease. Some studies suggest reduced harm from e-cigarette use compared with smoking, but this requires further study. Most adults who use e-cigarettes also smoke cigarettes; epidemiologic studies suggest that the combination of e-cigarettes and cigarettes is more harmful than using either product alone.”
“Immediate Physiological Effects of Acute Electronic Cigarette Use in Humans: A Systematic Review and Meta-analysis.”	Systematic Review	Larue, F. et al. [17]	Respir. Med. 2021	This study is a “meta-analysis of 27 studies assessing a wide range of physiological acute effects of e-cigarettes.”
“Vaping and Lung Inflammation and Injury”	Narrative Review	Park, J.A. et al. [18]	Annu. Rev. Physiol. 2022	“This comprehensive review discusses the diverse spectrum of vaping exposures, epidemiological and clinical reports, and experimental findings to provide a better understanding of EVALI and the adverse health effects of chronic e-cigarette exposure.”
“E-Cigarette Use, Small Airway Fibrosis, and Constrictive Bronchiolitis.”	Narrative Review	Hariri, L.P. et al. [20]	NEJM Evid. 2022	The authors “associate the histopathologic pattern of small airway–centered fibrosis, including constrictive bronchiolitis, with vaping, potentially defining a clinical and pathologic entity associated with e-cigarette use.”
“Biomarkers of Airway Immune Homeostasis Differ Significantly with Generation of E-Cigarettes.”	Narrative Review	Hickman, E. et al. [21]	Am. J. Respir. Crit. Care Med. 2022	“Results indicate disrupted immune homeostasis in fourth-generation e-cigarette users and demonstrate that the biological effects of fourth-generation e-cigarette use are unique compared with those associated with previous-generation e-cigarettes.”
“Health Effects of Electronic Cigarettes: An Umbrella Review and Methodological Considerations.”	Narrative Review	Travis, N. et al. [22]	Int. J. Environ. Res. Public Health. 2022	“This umbrella review underscores the urgent need for systematic reviews with better adherence to established reporting guidelines, consistent definitions of duration of e-cigarette use, a focus on newer devices, and accounting for the impacts of former or current smoking.”
“Systemic Biomarkers of Exposure Associated with ENDS Use: A Scoping Review.”	Scoping Review	Hiler, M. et al. [23]	Tob. Control. 2023	Twenty-seven studies that met the study criteria showed that “Biomarkers of most volatile organic compounds are lower in electronic nicotine delivery system (ENDS) users compared with cigarette smokers…. Evidence comparing metal exposures from exclusive ENDS use, cigarette smoking and dual use is mixed and depends on the metal.”
“Pulmonary Health Effects of Electronic Cigarettes: A Scoping Review.”	Scoping Review.	Gugala, E. et al. [24]	Health Promot. Pract. 2022	“Evidence indicates that EC use, especially dual use, leads to negative pulmonary effects and adverse outcomes. Education on the potential risks and publishing of EC ingredients on labels could help improve public health safety communication and reduce EC use.”
“The Role of Acrolein for E-Cigarette Vapour Condensate Mediated Activation of NADPH Oxidase in Cultured Endothelial Cells and Macrophages.”	Narrative Review	Kuntic, I. et al. [25]	Pflugers Arch. 2023	The authors note that “To better understand oxidative stress mechanisms, we have exposed cultured endothelial cells and macrophages to condensed E-cigarette vapour (E-cigarette condensate) and acrolein. In both endothelial cells (EA.hy 926) and macrophages (RAW 264.7), we have observed that E-cigarette condensate incubation causes cell death.”
“The Substitution of Fifty Percent of Combustible Tobacco Smoke Exposure with Either Electronic Cigarettes or Heated Tobacco Products Did Not Attenuate Acute Lung Injury in An Animal Model.”	Narrative Review	Husari, A. et al. [26]	Nicotine Tob. Res. 2023	Using an animal model, “substituting 50% of daily cigarette smoke (CS) exposure by either electronic cigarette (ECIG) or heated tobacco product (HTP) exposure did not result in significant attenuation of acute lung injury.”
“The Health Effects of Real-World Dual Use of Electronic and Conventional Cigarettes versus the Health Effects of Exclusive Smoking of Conventional Cigarettes: A Systematic Review.”	Systematic Review	Pisinger, C. et al. [27]	Int. J. Environ. Res. Public Health. 2022	“Existing studies indicate that dual use is at least as, or probably even more, harmful than ESCC. Due to the predominance of cross-sectional studies and the methodological weaknesses we judged the overall certainty of the evidence as ‘low certainty’.”
“Maternal Electronic Cigarette Exposure in Relation to Offspring Development: A Comprehensive Review.”	Narrative Review	Zhang, Y. et al. [30]	Am. J. Obstet. Gynecol. MFM. 2022	“Research suggests that maternal e-cigarette exposure may result in compromised neurodevelopment in newborns. In summary, current evidence is insufficient to rigorously evaluate the health impacts of maternal e-cigarette use on offspring development. Future investigations are warranted.”
“Physical and mental health outcomes associated with adolescent E-cigarette use.”	Narrative Review	Livingston, J.A. et al. [31]	J. Pediatr. Nurs. 2022	“Although somewhat less harmful than conventional cigarettes, e-cigarette use is related to a variety of negative physical and mental health outcomes among adolescent users.”
“Impact of Electronic Cigarettes on the Upper Aerodigestive Tract: A Comprehensive Review for Otolaryngology Providers.”	Narrative Review	Soo, J. et al. [32]	OTO Open. 2023	“Although e-cigs are likely less harmful than conventional cigarettes, preliminary research on e-cigs suggest several deleterious effects including in the upper aerodigestive tract. Due to this, there has been increased interest in restricting e-cig usage, particularly among the adolescent population, and caution in recommending e-cigs to current smokers.”
“The Nicotine and Tobacco Epidemic among Adolescents: New Products are Addicting Our Youth.”	Narrative Review	Heinly, A.; Walley, S. [33]	Curr. Opin. Pediatr. 2023	“Millions of adolescents continue to use nicotine and tobacco products, which puts them at risk for health problems, including nicotine addiction. Pediatric providers can provide prevention messages, screen youth for tobacco and nicotine use, and offer appropriate treatment options. Regulation of tobacco and nicotine products by the FDA is critical to reverse this public health epidemic of youth nicotine and tobacco use.”
“Molecular Imaging of Pulmonary Inflammation in Electronic and Combustible Cigarette Users: A Pilot Study.”	Narrative Review	Wetherill, R. et al. [34]	J. Nucl. Med. 2023	This is the first PET imaging study to compare lung inflammation between EC and cigarette users in vivo. We found preliminary evidence that EC users have greater pulmonary inflammation than cigarette smokers and controls, with a positive association between pulmonary and peripheral measures of inflammation.
“A Review of Toxicity Mechanism Studies of Electronic Cigarettes on Respiratory System.”	Narrative Review	Wang, L. et al. [35]	Int. J. Mol. Sci. 2022	This review summarizes the toxicity mechanisms and signal pathways of conventional cigarettes and e-cigarettes concerning the respiratory system, which could give researchers a better understanding and direction on the effects of e-cigarettes on our health.
“Electronic Cigarette Menthol Flavoring Is Associated with Increased Inhaled Micro and Sub-Micron Particles and Worse Lung Function in Combustion Cigarette Smokers.”	Narrative Review	Chandra, D. et al. [37]	Respir. Res. 2023	The authors “demonstrate utility of the HUMITIPAA as a predictive enabling technology to identify inhalation toxicological potential of emerging ECs as the chemical formulation of e-liquid gets modified.”