This article only applies to tobacco mixing cannabis smokers. They calculated the estimation by taking the ratio of tobacco death to user and applying it to the amount of estimated dagga smokers. Dagga has been proven not to cause lung cancers or diseases.

Cannabis 'kills 30,000 a year'
www.dailymail.co.uk
More than 30,000 cannabis smokers could die every year, doctors warn today. Experts writing in the British Medical Journal say cannabis could be a major contributor to UK deaths …read more