The investigators will identify a COPD cohort with ongoing symptoms or exercise limitation on HandiHaler, as proposed. The science behind this is why are people still limited (even if partially as determined using the CAT score) and is more distal airway targeting necessary? This doesn't necessarily mean targeting the acinar/alveolar beyond the terminal bronchioles, but just a little bit deeper into the distal conducting airway. This can be achieved with Respimat.