Journal of the American Medical Association put a dent in the arguments against Marijuana smoking today, with release of a new report showing casual pot smokers might even have stronger lungs than non smokers.

Researchers say that there is good evidence that occasional marijuana use can cause an increase in lung airflow rates and lung volume. Volume is measured as the total amount of air a person can blow out after taking the deepest breath they can.

The study, which was carried out by The University of California, San Francisco, and The University of Alabama at Birmingham, spans over more than two decades and involves more than 5000 men and women, in four American cities : Birmingham, Chicago, Oakland, Calif., and Minneapolis.

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.

The authors factored in for people who smoked tobacco and those that lived in more polluted areas with lesser air quality. The harm from cigarettes showed up clearly while those smoking a joint a day and not smoking tobacco did not show the degradation. Even one joint per week for twenty years did not appear to have significant effect.

Its not known exactly why tobacco appears to be so much more harmful than marijuana, especially considering the contents of the smoke are similar. It is known that THC, one of the main active cannabis oils in the herb, has anti inflammatory properties that may help to soothe the lungs. A part of the increased capacity was put down to the way pot smokers usually take deep breaths when they smoke, but one joint per day is hardly giving your lungs great exercise.

Obviously more research is needed, and it would be interesting to see results of lung tests in communities such as Jamaica and the Himalayas where smoking pot is endemic and done in larger daily volumes.

Written by Rupert Shepherd