Smoking cigarettes has long been linked to more heart attacks, largely because the chemicals that are in tobacco hurt our blood cells and increase the risk of atherosclerosis. This dangerous buildup of plaque in the arteries can make a heart attack more likely.
Secondhand smoke contains a lot of the same dangerous chemicals, which is why it can also hurt our hearts.
"No matter how much or how long you've smoked, quitting will benefit you," according to the National Institutes of Health.
Increasing evidence suggests that it may not just be tobacco that's bad — marijuana smoking might contribute to heart attack risk as well.
Because pot has been an illicit and illegal substance for so long, scientific studies on its long-term effects are still scant. But researchers studying heart attacks in people under 40 are worried about a possible link between two data sets: As heart attack rates have gone up in young people, so has their likelihood to report smoking marijuana. This doesn't prove anything, but it's a hint that more research is warranted.