my boyfriend was just told today that his lungs are enlarged;He has COPD,but herre's the bad news;He quit smoking 20 years ago when it became hard for him to breath1 He has had x-rays done several times in the past,never had enlarged lungs up-until now! So,doesn't mean that your situation is the same,but seeings how he hasn't smoked in over 20 years,it doesnt seem that lungs would reduce in size if you quit! But I'm sure because everyone is different,it doesnt mean that your lungs will not shrink back to normal size;just like my boyfriend;Meaing my boyfriend's lungs may shrink back also!This could be a change in weather or many other things going on!