BP	Blood pressure
ENDS	Electronic nicotine delivery system
FDA	Food and Drug Administration
FMD	Flow-mediated dilation
MRI	Magnetic resonance imaging
NC	Nicotine containing
NF	Nicotine free
NFEC	Nicotine-free e-cigarettes
PG	Propylene glycol
RCT	Randomized controlled trials
ROS	Reactive oxygen species
TPD	Tobacco Products Directive
VG	Vegetable glycerin