On average, a single cigarette takes 20 minutes off a person’s life, according to a new study published at University College London. To put that into perspective, a pack of 20 cigarettes can shorten a person’s life expectancy by seven hours.

A team of behavioral scientists at University College London has found that for long-term smokers, just one cigarette reduces lifespan by approximately 20 minutes. They have published an editorial in the journal Addiction outlining their study that examined the lifespans of smokers in the U.

Research shows each cigarette smoked can reduce life expectancy by up to 22 minutes, highlighting the dangers of smoking.

A new study conducted by researchers from University College London looked at the health impacts each individual cigarette can have on consumers’ lives.