One of the most serious risks of vaping? A condition called popcorn lung, or bronchiolitis obliterans. It's rare, but when it hits, it's permanentscarring the smallest airways in the lungs and causing Popcorn lung: What is it, and who is at risk? Harvard Health Doctors are warning about a rare but serious lung condition linked to vaping, known as popcorn lung (bronchiolitis obliterans). The disease causes permanent scarring in the lungs' smallest airways, leading to ongoing Vaping and Popcorn Lung: What You Need to Know About a Hidden Risk