Vaping has become increasingly popular among teens and adults alike, but medical experts are sounding the alarm about a hidden danger that could leave users with permanent and debilitating lung damage. The condition, known as bronchiolitis obliterans or more commonly “popcorn lung,” has no cure and can result in lifelong respiratory complications. Earlier this year, a 17-year-old who had been vaping for just three years was diagnosed with this irreversible disease, a stark reminder of how quickly and severely vaping can impact a person’s health. Donal O’Shea, a professor of chemistry at RCSI University of Medicine and Health Sciences, has issued a powerful warning about the risks of vaping and the toxic ingredients responsible for this condition. In an article published on The Conversation, Professor O’Shea explained how “popcorn lung” first came to public attention.

The condition was initially identified among workers at a microwave popcorn factory who were exposed to a chemical called diacetyl. This chemical was used to create the buttery flavor of popcorn and, when inhaled over time, caused severe lung damage. The same chemical is now found in some flavored vape liquids. When vaped, diacetyl is aerosolized and becomes a toxic substance that, once inhaled, damages the lungs permanently. According to Professor O’Shea, this exposure leads to inflammation and scarring in the bronchioles—tiny airways deep in the lungs—which progressively restricts airflow and makes breathing increasingly difficult. “There’s no cure for popcorn lung,” O’Shea emphasized. “Once the lungs are damaged, treatment options are limited to symptom management, which may include bronchodilators, steroids, and in the most severe cases, lung transplants. That’s why prevention is the only real protection.” Unfortunately, diacetyl isn’t the only threat. While the UK and EU have banned this chemical in e-cigarettes, it’s still present in products sold in other countries, including the United States. Even worse, diacetyl continues to be found in illegal and counterfeit vaping products, making regulation difficult and consumer safety questionable. Beyond diacetyl, there are many other hazardous substances in vape liquids. Professor O’Shea points out that volatile carbonyls such as formaldehyde and acetaldehyde have also been detected in the vapor emitted by e-cigarettes. These chemicals are known for their toxic properties and potential to harm the respiratory system. He further warns that there are more than 180 different flavoring agents currently used in vaping products. Many of these chemicals have not been tested for inhalation safety. Once heated, these flavorings can break down into entirely new and untested compounds. “Because users are exposed to so many different chemicals at once, it’s impossible to pinpoint diacetyl or any single ingredient as the sole cause of the disease in a specific case,” O’Shea noted. “But that doesn’t mean the risks aren’t real. Even if diacetyl isn’t the only factor, repeated exposure to a combination of harmful chemicals may greatly increase the likelihood of developing popcorn lung and other serious respiratory conditions.” What makes this all the more alarming is that many young people view vaping as a safer alternative to traditional smoking, unaware of the irreversible harm it could cause. The fruity or sweet flavors often appeal to younger audiences, and the absence of immediate symptoms may give users a false sense of security. However, the long-term consequences are only beginning to emerge—and they are dire. Professor O’Shea’s message is clear: prevention is not just better than cure—it’s the only defense we have against the lasting damage caused by vaping.