Pot smokers don't puff away lung health: study

Marijuana has proved to benifit in longer-term effect on lung functioning, suggests a new study.
Researchers found that multiple measures of lung function actually improved slightly as young people reported using more marijuana.
The new data come from a long-term study of more than 5,000 young adults in Oakland, Chicago, Minneapolis and Birmingham. From 1985 until 2006, researchers regularly asked participants about their past and current use of cigarettes and marijuana. They also tested how much air their lungs could hold and the maximum rate of air flow out of their lungs.
Not surprisingly, the researchers found that the more cigarettes their participants smoked or had smoked in the past, the worse their lungs performed on both tests, Kertesz's team reported Tuesday in the Journal of the American Medical Association.
But at least at moderate levels of pot smoking, that didn't seem to be the case -- in fact, the trend was reversed.
Lung volume and air flow rates both increased with each "joint-year" -- the equivalent of 365 joints or pipe bowls -- participants said they'd ever smoked, up until about seven joint-years, or some 2,555 joints.
It was a small overall improvement, though. Lung airflow -- measured by how much air people could blow out in one second -- was no more than 50 milliliters higher in pot smokers compared with non-smokers. The average value for a healthy male is four liters, according to Kertesz.
"It's a very real increase... but it's so small that I don't think that a person would feel a benefit in terms of their breathing," Kertesz said.