Vaporizing certainly ought to be easier on your lungs than smoking it, at least that's what I've always read. But I should think people with very sensitive lungs might still experience some trouble with vapors. And I should think it might depend on the strain of cannabis, too.

Are you by any chance being exposed to other irritants that could be making your pulmonary situation more unpleasant? Pollution? Animal dander? Cleaners or chemicals?

Have you tried edible cannabis to completely get around the pulmonary situation?