Vaping, which involves the use of electronic cigarettes and similar devices, has become a widespread practice. These devices function by heating a liquid solution, often called e-juice, into an aerosol that is then inhaled into the lungs. The central question is whether this regular inhalation affects measurable lung capacity and overall respiratory function. Given the rapid rise in use, the impact of vaping on the respiratory system is a major public health concern.
How Respiratory Function is Assessed
The standard method used by medical professionals and researchers to objectively measure lung function is called spirometry. This non-invasive test requires a person to take the deepest breath possible and then exhale all the air forcefully and quickly into a spirometer. The resulting measurements provide precise data points reflecting both the volume of air the lungs can hold and the speed at which air can be moved out.
Two specific metrics from this test are relevant to assessing lung capacity: Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1 second (FEV1). FVC represents the total amount of air a person can forcefully exhale after a full inhalation, measuring the overall lung volume. FEV1 measures the volume of air exhaled during the first second of that forced maneuver, indicating how easily air flows out of the lungs.
These measurements are often expressed as the FEV1/FVC ratio, which helps determine if reduced function is due to airway obstruction or restricted lung expansion. A lower FEV1 suggests an obstructive pattern, where narrowed airways slow airflow. A decreased FVC may point to a restrictive problem, where the lungs cannot fully expand. Comparing results to predicted values based on age, sex, and height allows clinicians to track reductions in respiratory capability.
Clinical Findings on Vaping and Lung Function
Peer-reviewed research suggests a measurable link between regular e-cigarette use and compromised lung function, particularly in adolescents and young adults. Cross-sectional studies show that young people who exclusively vape tend to have lower spirometric lung volumes compared to non-users. For instance, one study reported that e-cigarette users had an average FEV1 of 3.0 liters and FVC of 4.0 liters, compared to 3.5 liters and 4.6 liters, respectively, in non-users.
These reductions translate to a lower FEV1/FVC ratio, which is considered an early indicator of airflow obstruction in the small airways. Vapers in one study showed an average FEV1/FVC ratio of 75% compared to 79% in non-users, suggesting mild but chronic narrowing of the airways. Short-term studies also show that a single session of vaping can immediately increase airway resistance, making it harder for air to flow freely.
Regular vaping is associated with an increased prevalence of respiratory symptoms among adolescents, including wheezing, chronic cough, and shortness of breath. These symptoms indicate ongoing irritation and inflammation within the respiratory tract, which contributes to a decline in function over time. Vaping has also been linked to an increased risk of being diagnosed with asthma and experiencing more frequent attacks.
Beyond chronic effects, the outbreak of E-cigarette or Vaping Product Use-Associated Lung Injury (EVALI) highlighted the potential for acute, severe harm. Hospitalized adolescents with EVALI often exhibit significantly impaired lung function. While treatment can lead to improvement in FEV1 and FVC, some patients show persistent abnormalities on pulmonary function tests even after symptom resolution. Inflammatory markers and evidence of tissue damage in the lungs of vapers provide a physiological basis for the observed reduction in capacity.
Aerosol Components and Biological Mechanisms of Harm
The adverse effects on lung capacity are rooted in the chemical composition of the inhaled aerosol and its biological interactions within the airways. The e-liquid base typically consists of Propylene Glycol (PG) and Vegetable Glycerin (VG). While these are generally recognized as safe for ingestion, they are not inert when heated and inhaled, producing highly reactive compounds like formaldehyde and acrolein, which are known respiratory irritants.
Acrolein, a potent herbicide, can cause acute lung injury and is linked to chronic lung diseases. Inhaling PG and VG can induce lung inflammation, disrupt the function of epithelial cells lining the airways, and increase mucus concentration. These effects contribute to narrowed and obstructed air passages, ultimately reducing the efficiency of gas exchange and airflow, leading to a drop in FEV1 and FVC.
Many e-liquids contain Nicotine, which acts as a vasoconstrictor, causing blood vessels to narrow. Chronic nicotine inhalation contributes to pulmonary vascular remodeling, increasing blood pressure within the lungs and straining the right side of the heart. This vascular damage can indirectly impair overall lung function and capacity for gas exchange.
Flavoring chemicals, such as diacetyl, are significant contributors to lung injury. Diacetyl is associated with bronchiolitis obliterans, or “popcorn lung,” a condition causing scarring and irreversible narrowing of the small airways. Furthermore, heating coils in vaping devices can release ultrafine particles and heavy metals into the aerosol. These include lead, nickel, and chromium. These particulates penetrate deep into the lungs, triggering chronic inflammation, oxidative stress, and fibrosis, mechanisms that progressively destroy lung tissue and reduce capacity.