Asthma is a chronic inflammatory disease characterized by hypersensitive, swollen, and narrowed airways. When triggered, the muscles surrounding the bronchial tubes tighten, leading to an asthma attack with symptoms like wheezing, coughing, and shortness of breath. Vaping, or e-cigarette use, involves heating a liquid solution to create an inhalable aerosol. The relationship between inhaling this aerosol and the exacerbation of asthma symptoms has become a significant public health concern.
Key Components in Vape Aerosol
The aerosol produced by e-cigarettes is not simply water vapor but a complex mixture of chemicals derived from the heated e-liquid. The base of most e-liquids consists primarily of two humectants: Propylene Glycol (PG) and Vegetable Glycerin (VG). PG is a known respiratory irritant that can cause throat and airway dryness upon inhalation.
Nicotine is often present in varying concentrations, acting as the addictive component that can also affect lung function. E-liquids also contain flavorings, which are a major concern. Chemicals like diacetyl, used for buttery flavors, are known to cause severe respiratory disease when inhaled.
The process of heating the e-liquid components can also generate entirely new, hazardous compounds. When PG and VG are heated to high temperatures by the device’s coil, they can break down into volatile carbonyl compounds, such as formaldehyde and acetaldehyde. These irritants and ultrafine particulate matter are inhaled deep into the lungs, increasing the chemical burden on airway tissues.
How Vaping Irritates Asthmatic Airways
The already inflamed and hyperresponsive airways of a person with asthma react negatively to the chemical and particulate load delivered by the aerosol. Inhalation of the aerosol has been shown to impair the lung’s natural cleaning system, known as mucociliary clearance. This system relies on cilia, tiny hair-like projections, which sweep mucus and trapped particles out of the airways.
Exposure to the e-cigarette aerosol can reduce the frequency of the ciliary beat and even decrease the number of ciliated cells, causing mucus to build up and further narrow the bronchial tubes. The chemical irritants, particularly PG and flavorings, stimulate the airway lining to increase mucus production, a process linked to the upregulation of mucin proteins. This excess, stagnant mucus provides a perfect environment for inflammation and obstruction.
The most immediate danger is the direct triggering of bronchial hyperresponsiveness. The foreign particles and irritants prompt the smooth muscles surrounding the asthmatic airways to contract, leading to bronchospasm. The aerosol also drives a sustained inflammatory response in the lungs, increasing the infiltration of inflammatory cells like eosinophils and neutrophils. This exacerbates the chronic inflammation already present in asthma.
Clinical Evidence Linking Vaping and Asthma Attacks
Epidemiological studies consistently demonstrate a correlation between e-cigarette use and adverse respiratory outcomes, including the exacerbation of asthma. Research involving adolescents and young adults shows that those who use e-cigarettes have significantly increased odds of reporting an asthma diagnosis. One analysis found that current e-cigarette users had a 19% higher likelihood of having asthma compared to non-users.
Among individuals who already have asthma, e-cigarette users have been found to have nearly 24% increased odds of experiencing an asthma attack within a twelve-month period. Notably, this association holds even for adolescents who have never smoked conventional tobacco products, suggesting that the e-cigarette aerosol itself is an independent risk factor for respiratory issues. For individuals with pre-existing asthma, e-cigarette use elevates the likelihood of severe symptoms and hospitalizations.
Risks of Passive Exposure
The risks associated with e-cigarette aerosol are not confined to the person using the device, extending to those exposed to the secondhand or thirdhand emissions. Secondhand aerosol contains many of the same toxic chemicals, including nicotine, ultrafine particles, and breakdown products like formaldehyde, which are then inhaled by bystanders.
Studies have found that passive exposure to e-cigarette aerosol can worsen existing asthma and trigger acute flare-ups, particularly in children and adolescents. For example, youth with asthma exposed to secondhand e-cigarette aerosol have been shown to have higher odds of reporting an asthma attack in the past year.
Beyond the immediate cloud, thirdhand exposure occurs when aerosol residues like nicotine and irritants settle on surfaces and clothing, posing a lingering risk. Infants and young children are especially susceptible to these residues due to their developing respiratory systems and tendency to touch contaminated surfaces.