Months before the novel coronavirus took hold of the globe in late 2019, clusters of patients began appearing in emergency rooms throughout the US with a mysterious lung disease. Investigators quickly linked the illnesses not to a pathogen, but to patients’ use of vaping products. By examining the chemicals in these products, they eventually found a chief suspect: vitamin E acetate. The compound was being used as a cutting agent in some counterfeit or illicit cannabis-based vaping products. Still, many questions remain about how vitamin E acetate could have caused those injuries and whether it was acting alone. In this episode of Stereo Chemistry, host Kerri Jansen and C&EN senior reporter Britt Erickson sift through the complicated chemistry of vaping and explore some new evidence in the investigation. They’ll also discuss how the tragic events of last summer could prove to be a wake-up call for chemical regulators as they evaluate vaping products. A script of this episode is available at bit.ly/2ZJ1JjW. Find all of C&EN’s COVID-19 coverage at cenm.ag/coronavirus. Make a donation to support C&EN’s nonprofit science journalism at donate.acs.org. Image credit: Fedorovacz/Shutterstock