A large new government study has found that smoking marijuana on a regular basis, even over many years, does not impair lung function.
Dr. Donald Tashkin, a pulmonologist at the University of California, Los Angeles, who has studied marijuana for over 30 years and was not involved in the study, said it confirmed findings from several other studies showing “that essentially there is no significant relationship between marijuana exposure and impairment in lung function.” He said one reason marijuana smoke may not be as harmful as tobacco smoke, despite containing similar noxious ingredients, may be the fact that its active ingredient, THC, has anti-inflammatory effects.
“We don’t know for sure,” he said, “but a very reasonable possibility is that THC may actually interfere with the development of chronic obstructive pulmonary disease.”
Dr. Tashkin said he and his colleagues had found in their own research – unexpectedly – that even smoking up to three joints a day did not appear to cause a decrease in lung function. “I think that the bottom line is that there does not appear to be any negative impact on lung function of marijuana smoking,” he said, “and that therefore marijuana is not a risk factor for the development of C.O.P.D. Tobacco smoking is the most important risk factor for C.O.P.D.”