Over the past decade, cigarette smoking has continued to decline, but the use of electronic cigarettes (ECs) is rising. Current estimates are that about 4% of the U.S. population uses ECs, or vapes, as it is commonly termed. While ECs come in all shapes and sizes, they all use the same technology, as seen in the illustration. When turned on, a battery heats up a heating element which causes the liquid in the vaporizer chamber to aerosolize. The resulting aerosol is commonly and incorrectly called a vapor (vapor is the gaseous state of a substance). The liquid in the vaporizer chamber, or reservoir, is not water, but is either propylene glycol (antifreeze) or vegetable glycerin plus flavoring agents and additives (i.e. nicotine, cannabis oil). The heating coils are made from metal alloys that contain iron, chromium, carbon, nickel, or other metals.
Despite the perception of being less harmful than cigarettes, ECs are far from harmless. Their use is associated with adverse health consequences that not only affect the lungs, but the cardiovascular system as well. The variety of detrimental effects ranges from thermal injuries related to the malfunction of the battery or heating element to a recent cluster or respiratory illnesses suspected to be related to the use of ECs. When exposed to high temperatures, propylene glycol and vegetable glycerin decompose, generating harmful carbonyl compounds such as aldehydes including acrolein, formaldehyde, and acetaldehyde. These compounds cause oxidative stress resulting in increased cardiovascular risk, altered platelet function, airway epithelial (lining) damage, and disturbances in gas exchange function, or lung function. In addition, both cannabis and nicotine have been proven to cause damage to developing human brains, making the use of ECs in anyone under the age of 21 very dangerous.
Since April 2019, clusters of vaping-related acute lung injury (VpALI) have been reported and the incidence is rising. Most of these patients were previously healthy teenagers who developed rapid onset of symptoms, including cough and severe dyspnea (shortness of breath), after vaping. There have been a number of deaths, and, so far at least, it is more commonly seen in those whose ECs contained cannabis. The mechanism of lung injury is not yet well understood. Lung biopsies have shown chemical pneumonitis (lung inflammation). Hemoptysis (coughing up blood) has also been reported with cannabis vapers. Antibiotics have been helpful, but the specter of permanent, severe lung damage is real. The Centers for Disease Control (CDC) recommends routine screening of all patients for EC use, with subsequent counseling aimed at quitting for those who screen positive. Many patients with VpALI have reported using ECs obtained “from a friend of a friend” or ECs purchased on the streets, where they are cheaper.
Exposure to EC aerosols can be harmful and, unlike traditional cigarettes, may be acute and life-threatening. Careful investigation and research are needed to understand the clusters of VpALI cases, and ominously, many researchers feel that the cases of lung injury that have been seen so far may be just the tip of the iceberg.