Aerosol emitted from e-cigarettes is not harmless vapor but a source of air pollution that negatively affects both users and bystanders, according to a new study synthesizing two decades of research.
Gangnam Severance Hospital of Yonsei University said April 8 that Professor Byun Min-kwang of pulmonology, in collaboration with Loren E. Wold of Ohio State University and Laura E. Crotty Alexander of the University of California, San Diego, published findings highlighting the risks of e-cigarettes.
The research team analyzed more than 140 major studies worldwide, examining the impact of e-cigarette exposure across multiple organs.
E-cigarettes have often been perceived as less harmful than conventional cigarettes and have been used as alternatives or entry points to smoking. According to the Korea Disease Control and Prevention Agency, conventional smoking rates in Asia declined by about 12% last year compared with 2019, while e-cigarette usage rose by about 82%.
Recent studies have raised concerns about harmful substances in e-cigarettes and the aerosol generated during use. The liquid heated in e-cigarette devices turns into aerosol composed of nanoparticles smaller than fine dust, which can remain suspended in the air or be inhaled into the body.
The study found that nano-sized nicotine, heavy metals and toxic substances contribute to air pollution and penetrate deeply into the lungs and blood vessels during inhalation.
The most common effects of exposure include increased oxidative stress and inflammatory responses. Researchers concluded that e-cigarettes affect not only lung health but also the brain, cardiovascular system and metabolic functions, causing toxicity across nearly all organs.
E-cigarette users were found to have up to 1.4 times higher risk of metabolic syndrome compared with non-smokers. In women who use both conventional and e-cigarettes, triglyceride levels were reported to rise by as much as 3.9 times.
Nicotine and nanoparticles were also shown to damage vascular endothelial cells, contributing to atherosclerosis, elevated blood pressure and increased arterial stiffness.
The study further found that e-cigarettes can impair brain energy metabolism, trigger inflammation and reduce cognitive function. Lower glucose utilization in the brain may also worsen damage in the event of a stroke.
Researchers warned of “thirdhand smoke” risks, as aerosol particles can adhere to surfaces such as walls and furniture, persisting for months even after ventilation and posing direct toxicity risks to infants and pets.
The team also highlighted the broader environmental impact, citing projections from the journal Nature that air pollution-related mortality could double by 2050 if current emission trends continue.
Byun said the study reflects a broad academic consensus that e-cigarettes cause toxicity across multiple organs throughout the body, stressing the need for greater awareness among the public, policymakers and medical professionals about risks often masked by appealing flavors.
The study was published in the journal Annual Review of Pharmacology and Toxicology.
