Cilia grow back too . Fairly quickly too , everytime your sick (cold's flu's etc) you rip your cilia to "crap" well coughing. I just got over pneumonia and guess what cannabis actually helped me clear my lungs (it being an expectorant). If your looking for research on cannabis. Just make sure its independent. No taking the "national institute for drug addiction's" word as they directly profit from its illegality (much like pharmaceutical companies, my pills didnt help the pot did ....big surprise). Although I wouldnt reccommend smoking it people . Not with pneumonia anyway THAT was a mistake I did make .

Id stay away from any american (or any prohibitionist government) which makes claims contrary to testable science . Personally id like to slap my own countries health minister and the entire CMA....for refusing to even look at the research of independent countries such as australia and the netherlands....(not like the latter would have any idea about cannabis eh.....)