Andrew Huberman· PhD
they measured nicotine in the blood they are measuring how much people Vaped they were very careful about this one of the nice things about the vape pen for the sake of experiment and not recommending people Vape but they can measure how much nicotine is left in the vape pen before after they can measure how long they inhaled how long they held it in there's a lot that you can do that's harder to do with a cigarette