Eventually, she was vaping a nicotine cartridge a day, with the total amount of nicotine in one cartridge the same as that in a pack of cigarettes. “I didn’t think of myself as a smoker.

Vaping is still less common than cigarette use among U.S. adults, 4.5 percent of whom said they vaped in 2021. Nearly 8 percent of high school students reported vaping in the last month in a 2024 ...