Study: Many Smokers Unaware of Dangers to Heart and Brain

A study has revealed that many smokers are still unaware that smoking and exposure to second-hand smoke can increase the risk of heart attack and stroke. This is despite information about the health risks of tobacco having been communicated for decades.

The research analysed data from more than 240,000 adult smokers across 46 countries. The findings were reported in the journal BMJ Open.

Researchers found that more than 90 per cent of smokers already knew that smoking can cause lung cancer. However, knowledge of the impact of smoking on other deadly diseases remains much lower.

Only around 80 per cent of respondents knew that smoking contributes to heart disease and heart attacks. Meanwhile, only around 70 per cent were aware that smoking can cause stroke.

More worryingly, there has been little progress over nearly two decades in public knowledge of the various health risks associated with smoking. “The knowledge gaps regarding the major health impacts of smoking and the dangers of second-hand smoke are deeply concerning,” said Janet Chung-Hall, the study’s lead researcher and a scientist for the International Tobacco Control Policy Evaluation Project at the University of Waterloo in Canada.

According to Chung-Hall, the low awareness of smoking’s impact on the cardiovascular system is particularly alarming. Smoking is said to cause more than 2 million deaths from cardiovascular disease worldwide each year.

“Raising public awareness of these risks should be a greater public health priority,” she said, as reported by US News on Monday (17/8/2026).

The study also found similar problems regarding knowledge of the dangers of second-hand smoke, or passive smoking. In fact, in most of the high-income countries studied, knowledge of the health risks from second-hand smoke has actually declined. These countries include Canada, the United States, New Zealand, the United Kingdom and Japan.

Although around 90 per cent of respondents knew that smoking causes lung cancer, only 77 per cent knew that exposure to second-hand smoke can also cause lung cancer.

These findings show that knowledge of the dangers of smoking does not always extend to the risks faced by those around smokers.

Geoffrey Fong, an expert in psychology and public health sciences at the University of Waterloo and one of the researchers, said that knowledge is an important first step in encouraging someone to quit smoking and in protecting others from second-hand smoke exposure. “Knowledge is an important first step to quitting smoking and protecting others from second-hand smoke exposure,” Fong said.

According to him, the research findings demonstrate the need for governments to implement stronger and more sustained public education on the various dangers of smoking and second-hand smoke, particularly the risks to the heart and blood vessels as well as cancer risks.

“More effective health communication policies, such as graphic warnings on tobacco products and sustained media campaigns, can help raise public awareness,” Fong said.

Such efforts are expected not only to encourage existing smokers to quit, but also to help young people better understand the dangers so they can be prevented from starting to smoke.

Previous studies on cigarette packaging warnings have also shown that larger, graphic warnings with more complete information are more effective in conveying the health risks of smoking.