On the occasion of World No Tobacco Day Thursday, the UN health agency hailed that smoking had declined significantly since year 2000, but warned that there were still far too many people indulging in the dangerous habit.
And it cautioned that research showed there was "a serious lack of knowledge" about the different health risks associated with tobacco.
Tobacco use has been linked to more than seven million deaths worldwide each year, including some 890,000 from breathing in second-hand smoke.
But many people are unaware that nearly half of those deaths, around three million, are due to cardiovascular disease, including heart attacks and stroke, WHO warned.
"Most people know that using tobacco causes cancer and lung disease, but many people aren't aware that tobacco also causes heart disease and stroke - the world's leading killers," WHO chief Tedros Adhanom Ghebreyesus said in a statement.
"Tobacco doesn't just cause cancer. It quite literally breaks hearts," he said.