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 == Cannabis == 

 I have reverted this edit. The source describes two case reports of people who used cannabis and developed emphysema (with bullae) and aspergillomas, with subsequent pneumothoraces. The reference is a primary source, and in any case concentrates more on the connection between cannabis and aspergillus. The presence of pneumothoraces is incidental. Perhaps more importantly, my main secondary sources do not describe cannabis use as a cause for pneumothorax, I am inviting the anonymous IP editor to comment.  ¤  "