The health worries you have after smoking can last for years after you stubbed out your final cigarette.

It all depends, a new research study from South Korea shows, on how long a person smoked and how heavily.

Cardiovascular disease is not the only toll smoking takes, but it’s one of the deadliest. It can lead to heart attacks, strokes, and heart failure.

The study looked at more than 5.3 million South Koreans. They took a deep dive into the health records of the mostly male participants, who had an average age of almost 46. Roughly 16% were current smokers, almost 2% had quit, and 82% had never smoked.

Researchers tracked the participants an average of 4 years and two months, monitoring cardiovascular disease development. They recorded each participant’s smoking history.

Depending on how much and how long someone smoked, they found, the path to cardiovascular health could take a few years to more than 20.

The study’s “tipping point” was eight so-called “pack years” of smoking. They calculated a pack-year by multiplying the number of packs smoked per day by the number of years a person smoked.

Smoking one pack a day for eight years would equal eight pack years. So would smoking two packs a day for four years.

Those who quit smoking before eight pack years are lucky. Their cardiovascular risk drops quickly and their heart health returns to that of someone who never smoked between five and 10 years.

For smokers with more than eight pack years, it takes about 25 years to equal the heart disease risk of a never-smoker.

So don’t start smoking. If that ship has sailed, quit as soon as you can. Every extra puff counts.