A 2020 study published by researchers at UCSF found that JUUL delivers five times more nicotine to the blood, per puff, than a Marlboro.
Maier, Scott. "JUUL Delivers Substantially More Nicotine than Previous Generation E-Cigs and Cigarettes." USCF News. 6 January. 2020. Article.https://www.ucsf.edu/news/2020/01/416371/juul-delivers-substantially-more-nicotine-previous-generation-e-cigs-and#:~:text=JUUL%20delivers%20substantially%20more%20nicotine%20to%20the%20blood%20per%20puff,study%2C%20which%20appears%20online%20Jan.