"Popcorn lung" is the common name for bronchiolitis obliterans, a serious and irreversible lung disease that damages the smallest airways. The name comes from an outbreak in a microwave popcorn factory in the 1990s, where workers exposed to diacetyl (buttery flavoring) developed the condition.
Here's what's true and what's myth:
| Claim | Status | Evidence |
|---|---|---|
| Diacetyl causes popcorn lung in factory workers | True | Well-documented in occupational settings with high airborne concentrations (NIOSH) |
| Some e-liquids contain diacetyl | True | Multiple studies have found diacetyl in buttery, creamy, and some fruit flavored e-liquids |
| Vaping causes popcorn lung | Not proven | No confirmed cases of bronchiolitis obliterans from vaping. The exposure levels in vaping are orders of magnitude lower than factory settings |
| Popcorn lung is a widespread vaping health crisis | Myth | Despite hundreds of millions of vapers worldwide, there are zero confirmed cases of popcorn lung from nicotine vaping |
This does NOT mean diacetyl in e-liquid is safe. It means the risk is dose-dependent, and the doses from vaping are much lower than the doses that caused disease in factory workers. The concern is real but the risk level is often exaggerated in popular reporting.
FDA has asked manufacturers to provide safety data on diacetyl and other flavoring chemicals, and the PMTA process requires toxicology testing. But as of 2026, most flavored products on the market have not gone through this review — they remain on shelves under enforcement discretion.
