One of the study's co-authors, Stefan Kertesz commented :
"At levels of marijuana exposure commonly seen in Americans, occasional marijuana use was associated with increases in lung air flow rates and increases in lung capacity ... With marijuana use increasing and large numbers of people who have been and continue to be exposed, knowing whether it causes lasting damage to lung function is important for public-health messaging and medical use of marijuana."
He continues that even at daily usage levels of one joint per day over seven years, people were not seeming to have any degradation of lung capacity or function.