This research study will be evaluating whether liquid nitrogen sprayed on the cells lining the airways (cryotherapy) can reduce the mucus produced in the lungs of patients with chronic obstructive pulmonary disease (COPD). The study involves bronchoscopies, (placement of a lighted, flexible scope into the lungs) under general anesthesia to deliver the treatment to the lungs. The study is randomized such that 2/3 of individuals get the cryotherapy and the other 1/3 get a sham (control) treatment with no cryotherapy. Participants in the sham control group will be evaluated for eligible for cryotherapy at end of year one. The Study duration is 36 months. Those initially randomized to the treatment group, they will have 7 clinic visits and 2 treatment visits. Participants randomized to sham group will have 11 clinic visits and 4 treatment visits.