Young adults who smoke are eight times as likely to suffer a major heart attack compared to peers who don’t smoke or gave it up, researchers in the United Kingdom found. The study published Tuesday in the journal Heart was led by researchers at Sheffield Teaching Hospitals NHS Foundation in partnership with the University of Sheffield.

“All smokers are at much greater risk, but younger smokers are particularly vulnerable and are over eight times more likely to have a major heart attack than their non-smoking peers. An awareness of this strikingly higher risk is an essential public health message and could allow effective targeted intervention,” Ever Grech, consultant cardiologist at Sheffield Teaching NHS Foundation Trust, said in a statement.

Grech added that many people underestimate the health risks associated with smoking. “Many patients seem aware there are some risks of a heart attack with smoking, but they were blissfully unaware that the risks were anything more than slightly higher than usual,” Grech told Reuters.

The study analyzed data collected from 1,727 adults undergoing treatment for a type of heart attack known as a STEMI or ST-segment elevation myocardial infarction from 2009 to 2012. A STEMI is the typical pattern seen on the electrocardiogram indicating that a large portion of the heart muscle is dying. Close to half of the 1,727 adults (48.5 percent) were current smokers, over 27 percent gave up smoking and just over 24 percent never smoked.

Researchers also used data from the Office for National Statistics Integrated Household Survey (ONS-IHS), for the South Yorkshire region that collects information on the prevalence of smoking in the region.

The researchers found that smokers under the age of 50 are the most vulnerable across all age groups of smokers with their chances of suffering a heart attack being eight times higher than non-smokers.

Researchers also found that smokers between 50- 60 years of age were five times as likely to have a major heart attack whereas smokers over the age of 65 have a three-fold increase in risk compared to non-smokers.

“All current smokers must be encouraged into smoking cessation therapy to reduce their risk of acute STEMI, with a focus on the youngest smokers whose increased risk is often unrecognized,” Grech said in the statement.