The reason it started after you stopped smoking Derek as all the small hairs in your lungs were stuck to your lungs so when dust came into your lungs they didn't irritate them now your lungs are recovering the hairs grow back an start to get irrateded so you cough .a went to dr Boyd in Glasgow an was told wear a mask an u will be fine but a wasn't so spoke to him to tell him a was having same same symptoms an his reply was the bloom must be in your hair or in your clothes an as you no am as bald as a coot so wore a coat an a mask problem solved.