Health officials have long argued there’s no safe amount of smoking—but, even still, many people assume a cigarette here and there doesn’t hurt. A new study published in the Lancet Respiratory Medicine puts that notion to rest: It found smoking just a handful of cigarettes per day causes lung damage similar to smoking more than a pack per day.
The study examined the smoking habits and health of more than 25,000 Americans ages 17 to 93. At baseline, each person told the researchers how much they smoked (as well as general information about their health, demographics and lifestyle) and had a spirometry exam, which assesses lung function by measuring how much air can be exhaled in a second, as well as how much air the lungs can push out in total after taking a deep breath. Participants were then tracked for up to 20 years, during which time they had at least one more spirometry test to assess changes in lung health.