Pretty much everyone is aware that smoking is bad for you. But unfortunately, some people still do it anyway.

For the study, researchers analyzed 141 cohort studies from 1946 to 2015 on smoking and heart disease to try to figure out how many daily cigarettes it takes to raise your risk of heart disease and stroke.

The researchers broke data down into people who smoked one, five, or 20 cigarettes a day, and compared it with people who never smoked.

Here's what they found: Having just one cigarette a day significantly increases your risk of heart disease and stroke. For men, smoking one cigarette a day raised a person's risk of heart disease by 48 percent on average over a non-smoker, while smoking 20 cigarettes a day doubled the risk.

It was even worse for women: Having one daily cigarette increased their heart disease risk by 57 percent, while smoking 20 cigarettes a day raised the risk by 2.8 times.

Heart disease is currently the No.1 cause of death in the U.S., per data from the Centers for Disease Control and Prevention, and stroke isn't far behind. So really, this isn't something you want to mess with.

The researchers point out that, while it's good to cut back on smoking if you're a heavy smoker, it's much, much better to cut out the habit entirely.

Smoking only about one cigarette per day carries a risk of developing coronary heart disease and stroke much greater than expected: around half that for people who smoke 20 per day, the researchers wrote in the conclusion. No safe level of smoking exists for cardiovascular disease.

In an accompanying editorial, Kenneth Johnson, an adjunct professor of public health at the University of Ottawa, writes that any exposure to cigarette smoke is too much. If you're rethinking your smoking habit or trying to urge a loved one to do the same, just know that you'll have a much better impact on your health if you completely break the habit.