The rise and fall of e-cigarette cloud chasing appealing to youth.

Electronic cigarette (e-cigarette) use continues to rise among youth with new devices and technology outpacing regulation. The "cloud chasing" phenomenon, whereby vapers compete or otherwise showcase the production of large or artistic exhaled aerosols from e-cigarettes, played a role in the early appeal of e-cigarette use in youth. This paper describes the sudden rise in the phenomenon of cloud chasing on social media and at vaping conventions due to the proliferation of second and third-generation powerful e-cigarette devices in their peak in 2015 and then their subsequent decline in the past few years. We describe four distinct factors that affected both the rise and fall in cloud chasing, including: 1) the rapid evolution of powerful e-cigarette devices, 2) the increase in social media promotions, 3) an inability of regulatory bodies to keep up with evolving ENDS technology, and 4) two recent widespread health concerns and conditions. Conclusions highlight the importance of swift regulation and effective health communication to mitigate unintended consequences of product evolution. It remains unknown whether such vape tricks and related competitions will reemerge and appeal to youth as store fronts reopen and devices continue to evolve.