Moderate Pot Use May Boost Lung Capacity It's all that deep inhaling, suggests a study By Matt Cantor, Newser User Posted Jan 10, 2012 6:05 PM CST 41 comments Comments A woman smokes marijuana at the San Francisco Medical Cannabis Clinic in San Francisco. (AP Photo/Eric Risberg, File) (Newser) – A new study sure to warm the hearts of pot smokers: Puffing marijuana apparently doesn't hurt your lungs the way tobacco does, a quirk that probably has more to do with the way people smoke it than the pot itself, reports the Washington Post. In fact, pot smoking might even improve your lung capacity. Researchers measured it in 5,000 subjects over 20 years and saw improvements among moderate users of the drug. Moderate use, the researchers note, is common among marijuana smokers: They often have a few joints weekly and use less as they get older. Tobacco users smoke far more frequently over longer periods. Pot users' deep inhalation and chest inflation may be behind the improved lung capacity. Heavy marijuana use, however, probably negates that because pot and tobacco have many of the same compounds. The study in the American Medical Association is here. Or click here to read how middle-aged pot smokers have sharper minds.