[bigfootbob]

"I think we can all agree that the ingestion of smoke into the lungs cannot be particularly beneficial to pulmonary function."

This is not completely true. Dr. Greenspoon and others have found that asthmatic patients benefited from the induction of small amounts of smoked or vaporized cannabis. One of the active ingredients in marijuana is a bronchodilator, (opens the constricted airways), without the severe side effects of other asthma inhalers, like synthetic steroids or beta-agonists.

[jayef]

True. Unlike tobacco, marijuana tends to inflame only the large passageways of the lungs. That is why is does not cause/exacerbate bronchitis and emphysema. As you suggest, because of its vasodilative properties, cannabis may in fact be useful in the treatment of both.