Just 60 seconds of second-hand cannabis could damage blood vessels, a new study has found.

Scientists also point out that it may take people three times longer to recover after inhaling such smoke compared to normal tobacco fumes. Furthermore, with the damage to blood vessels, experts fear regular inhaling of second-hand marijuana smoke could lead to strokes and heart attacks.

Researchers at the University of California monitored the blood vessels of rats before and after exposing them to both second-hand cannabis and tobacco smoke. It was found that the arteries which carry blood to the organs were weakened for around 90 minutes after cannabis, whereas tobacco was an average of 25 minutes of impairment.

Lead author Dr Matthew Springer explained that rats' blood cells are similar to humans, meaning the results would more than likely be the same. He noted that it was the plant materials from cannabis which proved to be harmful.

"Many people still assume that marijuana second-hand smoke is benign," he explained. "While the public health community has strongly advised people to avoid tobacco second-hand smoke for many years, it has not made comparable pronouncements about marijuana second-hand smoke.

"The public’s perception of risk from marijuana second-hand smoke has thus been limited to a few publicised studies. Increasing legalisation of marijuana makes it more important than ever to understand the consequences of exposure to second-hand marijuana smoke."

Around 2.3 million adults and teenagers in the U.K. use cannabis each year, making it the most common banned substance. The drug has also been linked to anxiety, depression and insomnia.

Findings were published in the Journal of the American Heart Association.

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