Pulmonary diacetyl for vaping and popcorn is often added to flavored e-liquid to improve flavor. Inhaling diacetyl causes inflammation and can cause permanent scarring on the smallest branches of the respiratory tract (popcorn), making it difficult to breathe. Popcorn lung has no lasting treatment. Inhaled vapor can also cause inflammation in the mouth and eventually cause gum disease.
In addition, vaping has been shown to destroy mitochondria used in wound healing. Over time, inhaling the particles in the vapor can cause what has become a well-known smoker's cough. Michele Hart, clinical pulmonary nurse at Baystate Pulmonary Rehabilitation, points out that vaping coats the lungs not only with steam but also with harmful chemicals. Like the vapor inhaled by the user of the vaporizer, the second-hand vapor created by a device contains the same potentially harmful chemicals.