No lung damage from moderate smoking of cannabis

For the cannabis smokers among us there's good news. A new study has been released by JAMA, the Journal of the American Medical Association, which concludes that moderate cannabis smoking (up to 1 joint per day) does not negatively affect the functioning of the lungs. But it doesn't stop there. The study even shows that there's a slight increase in lung airflow rates and an increase in lung volume. The authors speculate that aspects of the way cannabis smokers inhale -- deeply and holding the smoke in for as long as possible before exhaling -- may actually strengthen lungs and increase their capacity.

The study has been done by researchers at the University of California, San Francisco, and the University of Alabama at Birmingham. More than 5100 men and women took part in this study over a period of 20 years. All individuals were regularly asked about recent smoking of cannabis and/or tobacco. During the study everyone had several lung function checks and the authors calculated the effects of tobacco and cannabis. They also considered other factors that could have an impact on the functioning of the lungs, including air pollution. The analysis revealed that smoking cannabis did not seem to cause harm to lung functioning, however cigarette smoking did. The test results from cigarette smokers' worsened gradually during the study, but smoking cannabis as often as one joint daily for seven years, or one joint weekly for 20 years was not linked with worse results.

"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," said Stefan Kertesz, one of the study's co-authors. "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."

Source:
Washington Post
JAMA, Journal of the American Medical Association