• Smoking is the most common cause of emphysema, a chronic lung condition resulting from air sacs becoming stretched and damaged.
  
• In a new study, researchers found that airway inflammation and emphysema are more common in people who smoke cannabis compared to cigarette smokers and non-smokers.
  
• “93% of the marijuana smokers had emphysema rather than 67% of the tobacco-only smokers,”
  
• The researchers also found that cannabis smokers had higher rates of airway inflammation.
  

For complete study 

Also See Does Marijuana Cause Lung Cancer? (webmd.com)