Does vaping cause popcorn lung?

According to Cancer Research UK, there is little to no evidence that using e-cigarettes will result in "Popcorn Lung" (bronchiolitis obliterans). In 2015, a few studies caused a media frenzy when they published results stating that there was a link between breathing in a chemical called diacetyl and Popcorn Lung. However, the cluster of people affected by this very rare lung condition were factory workers in a a popcorn factory. The illness was not related to the use of e-cigarettes. 

Nevertheless, as a safety precaution, vaping companies and flavor manufacturers have since completely eliminated diacetyl from their products. In 2016 the UK completely banned diacetyl. Today most vape juices are completely diacetyl-free while others may contain diacetyl in levels hundreds of times lower than in cigarette smoke.