380,000 ‘non-smokers’ regularly smoke cannabis, putting their health at risk
A new study published in the journal Addiction finds significant levels of cannabis use among people who classify themselves as non-smokers . The UCL-led analysis of a survey of adults in Great Britain found that 5% of self-identified non-smokers are past year cannabis users with an estimated 380,000 smoking cannabis with or without tobacco at least weekly.
Hannah Walsh, King’s College London, one of the study’s authors said the findings raised concerns that non-smokers were unaware that smoking cannabis carries similar health risks to tobacco:
“It is extremely concerning that there are hundreds of thousands of people who do not see themselves as ‘smokers’ but are none-the-less smoking every week. It is possible that they do not realise they are putting their health at risk. It’s also a concern that people may be unwittingly establishing a tobacco addiction as a consequence of their cannabis use.”
A further 830,000 tobacco smokers also smoke cannabis at least weekly meaning that there may be around 1.2 million at least weekly cannabis smokers in Great Britain. Long term smokers of cannabis have an increased risk of many of the same diseases that tobacco smokers do.  Furthermore those who mix cannabis with tobacco are at risk of establishing a tobacco addiction which can be very difficult to break. 
In the UK, in common with other parts of Europe, cannabis is usually consumed by smoking it with tobacco. In other parts of the world, particularly the Americas, while cannabis is still usually smoked, it is much less common to smoke cannabis combined with tobacco.
Hazel Cheeseman, Director of Policy at Action on Smoking and Health, said:
“Government generally sees cannabis and tobacco as separate issues but plainly their use is deeply interwoven in our country. There is an opportunity to address this in the Government’s planned Addiction Strategy and Tobacco Control Plan. This strategy must include measures to tackle the overlapping use of cannabis and tobacco and the resulting harm to health.”
The study found that cannabis was disproportionately used among younger people with 70% of people who had used cannabis in the last year being under 39. It also found that those who reported using cannabis and tobacco together were more likely to report mental health problems than those who used either product on its own.
Notes to the editor:
Action on Smoking and Health is a health charity working to eliminate the harm caused by tobacco use. For more information see: www.ash.org.uk/about-ash. ASH receives funding for its programme of work from Cancer Research UK and the British Heart Foundation.
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 For a copy of the paper in advance of the embargo lifting email firstname.lastname@example.org. For a copy of this paper after the embargo has lifted, please contact Jean O’Reilly, Editorial Manager, Addiction, email@example.com
Chandni Hindocha, Leonie S Brose, Hannah Walsh, Hazel Cheeseman. Cannabis use and co-use in tobacco smokers and non-smokers: prevalence and associations with mental health in a cross-sectional, nationally representative sample of adults in Great Britain, 2020. Addiction. December 2020
The survey work was undertaken by YouGovfor ASH. Total sample size was 12,808 adults 18+ in Great Britain. Fieldwork was undertaken online by YouGov between 17th February 2020 and 11th March 2020. Respondents are weighted to be representative of GB population.
 NHS England. Cannabis: the facts. Accessed December 2020
 Chaiton M, Diemert L, Cohen JE, et al. Estimating the number of quit attempts it takes to quit smoking successfully in a longitudinal cohort of smokers. BMJ Open 2016;6:e011045. doi: 10.1136/bmjopen-2016-011045
 Hindocha, Chandni et al. “No Smoke without Tobacco: A Global Overview of Cannabis and Tobacco Routes of Administration and Their Association with Intention to Quit.” Frontiers in psychiatry vol. 7 104. 5 Jul. 2016, doi:10.3389/fpsyt.2016.00104
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