Bad lungs

The impact of e-cigarettes on lung health is clear and multifaceted. Although they may avoid most of the harmful substances produced by traditional cigarettes through combustion, current scientific evidence indicates that the aerosol of e-cigarettes itself directly damages the respiratory system, and its risks cannot be ignored.

 How e-cigarettes harm the lungs: Core mechanisms
The harm of e-cigarettes to the lungs is not through a single pathway but through multiple mechanisms working together, affecting cells and overall organ function negatively.

Triggering oxidative stress: The aerosol of e-cigarettes itself has oxidative potential and, after inhalation, directly increases the oxidative stress level in the lungs. A 2025 mouse experiment showed that acute exposure to e-cigarette aerosol for 30 minutes led to a 60% increase in the oxidative potential of the lungs and a significant increase in oxidative lipid levels. This oxidative stress is a key step in initiating inflammatory responses and causing lung tissue damage.

Triggering inflammatory responses: E-cigarettes amplify the inflammatory response in the lungs. Studies have found that nicotine itself plays a core role in triggering lung inflammation related to e-cigarette use. At the same time, the vapor of e-cigarettes enhances the inflammatory signals related to lung injury, making the lungs more vulnerable to damage.

Damaging the airway barrier: The airway epithelium is the first line of defense in the lungs. E-cigarette exposure damages the barrier function of lung epithelial cells, leading to increased cell permeability, and causing cytoskeleton rearrangement and gap formation. This weakens the lungs' ability to resist harmful substances from the outside.

Causing cellular-level changes: Single-cell sequencing analysis of young e-cigarette users' small airways revealed that the composition of airway cells has changed, with an increase in the proportion of immune cells (such as neutrophils) and goblet cells that secrete mucus, accompanied by small airway ventilation defects. This indicates that e-cigarettes have already caused potential harm to the lungs at the cellular level in young people.

Association with respiratory diseases
These mechanisms directly translate into an increase in the risk of various respiratory system diseases.

Respiratory symptoms and chronic obstructive pulmonary disease (COPD): A 2025 systematic review and meta-analysis provided moderate certainty evidence that current e-cigarette users without a history of smoking have a significantly higher risk of developing respiratory symptoms (relative risk RR = 1.90) and a trend of increased risk of COPD compared to never users.

Asthma: E-cigarette use increases airway hyperresponsiveness and the incidence of asthma.

E-cigarette or vaping product use-related lung injury (EVALI): This is an acute or subacute severe respiratory system disease that first broke out on a large scale in the United States in 2019. Its symptoms include coughing (88%), shortness of breath (80%), and fever (76%), and imaging often shows bilateral ground-glass opacities. The condition can deteriorate rapidly, with 76% of patients requiring admission to the ICU and 8% requiring mechanical ventilation. EVALI is strongly associated with the use of e-cigarette products containing vitamin E acetate (often used as a thickener in THC products), but there are also case reports of non-contains this substance. Data from the World Health Organization (WHO) shows that as of February 2020, the United States has reported 807 cases of EVALI and 68 deaths.

⚠️ Limitations of "relatively less harmful" and the risk of dual use
The statement that "e-cigarettes are less harmful than cigarettes" is based on a complete substitution premise.

Higher risk of dual use: If traditional cigarettes and e-cigarettes are used simultaneously (dual use), it does not reduce the risk. Meta-analysis shows that the risk of respiratory symptoms in dual users is 2.53 times that of never users, and the risk of COPD is 3.86 times, with risk levels similar to those of traditional smokers, and even possibly higher due to exposure to more harmful substances.

The position of authoritative institutions: The WHO clearly states that e-cigarettes are not harmless. Their toxic chemicals can damage the lungs and cause heart diseases, and they are not recommended as an alternative for quitting smoking. The CDC of the United States also emphasizes that no tobacco product (including e-cigarettes) is safe. The aerosol in e-cigarettes contains carcinogenic chemicals and tiny particles that can penetrate the lungs.

Summary
E-cigarettes are not completely harmless to the lungs. They directly damage the respiratory system through mechanisms such as oxidative stress, inflammation, and destruction of the airway barrier, and are associated with respiratory symptoms, COPD, asthma risks, and even potentially causing EVALI, a serious acute lung injury. Although their harm may be lower than the smoke from traditional cigarettes, "lower harm" does not mean "safety". For non-smokers, especially teenagers, using e-cigarettes only brings health risks with no benefits. If you or someone around you is using e-cigarettes and experiencing symptoms such as coughing, chest pain, and breathing difficulties, please seek medical attention immediately.