Evan's friends have become increasingly concerned about his health these days. He has always been a very active and outgoing person, but these days, simple activities like mowing the lawn or taking out the trash tire Evan out. He dismisses the problem, saying that anyone would expect to slow down a bit at the age of 50. But Evan's friends have noticed other symptoms that they find troubling. He complains of a tight chest and he appears to spend a lot of effort breathing, even when he is at rest. Evan has smoked cigarettes as long as his friends can remember, and despite his inability to do any exercise, he has remained very thin. Sometimes it looks like Evan is puffing his chest out, and Evan often jokes, "My lungs must be a nice place to hang out, because sometimes it seems like the darn air just doesn't want to go out!" Evan is most likely suffering from