Long-term marijuana smokers are prone to develop bullous lung disease at a much younger age than cigarette smokers, possibly because they tend to inhale more deeply and hold hot smoke in their lungs up to four times longer, researchers say.

The disease, also known as bullae, obstructs breathing and causes destruction of lung tissue. It can impact smokers of all substances, but researcher Matthew Naughton and colleagues found that marijuana smokers typically get bullae 20 years sooner than tobacco smokers -- at around age 41 rather than 65.

"What is outstanding about this study is the relatively young ages of the lung disease patients, as well as the lack of abnormality on chest X-rays and lung functions in nearly half of the patients we tested," said Naughton. "Marijuana is inhaled as extremely hot fumes to the peak inspiration and held for as long as possible before slow exhalation. This predisposes to greater damage to the lungs and makes marijuana smokers are more prone to bullous disease as compared to cigarette smokers."

The study appears in the January 2008 issue of the journal Respirology.