Cannabis ‘may be worse than tobacco smoke for the lungs’

Cannabis smoke may be worse than tobacco smoke for the lungs, a new study has suggested.

The researchers compared cannabis smokers, tobacco-only smokers and non-smokers and found that airway inflammation and emphysema are more common in people who smoke cannabis than tobacco smokers.

Dr Giselle Revah, a cardiothoracic radiologist at Ottawa Hospital in Canada, told AFP: "Marijuana smoking is on the rise and there's a public perception that marijuana is safe, or that it's safer than (tobacco) cigarettes.”

"But this study raises concerns that this may not be true."

Revah suggested that the habit of smoking without a filter by marijuana users may be behind the difference.

She said: "Marijuana is smoked unfiltered, versus tobacco which is usually filtered. When you're smoking unfiltered marijuana, more particulates are reaching your airways, getting deposited there and irritating your airways."

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“People usually take bigger puffs and hold the smoke in their lungs longer for marijuana, which may lead to more trauma to those air spaces."

The researchers wrote: "In this era of legalisation and increasing consumption of marijuana, we sought to identify the imaging features of marijuana smoking on chest CT scans.

“We found higher rates of emphysema among marijuana smokers (42 of 56, 75%) than among nonsmokers (three of 57, 5%) and among age-matched marijuana smokers (28 of 30, 93%) than among tobacco-only smokers (22 of 33, 67%).”

The study is small, however, and the researchers caution that there are problems including the fact that marijuana smokers also smoke tobacco, preventing strong conclusions being drawn.

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The researchers said: “Further larger and prospective studies are necessary to confirm and further elucidate these findings, as marijuana use is bound to increase in the future, given the increasing legalisation of its use for medical and recreational purposes.”

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