Chronic obstructive pulmonary disease, or COPD, is a long-term lung disease that makes breathing more difficult. It's important to understand the four stages of COPD - mild, moderate, severe and very severe - and how to reduce exposure to anything that can worsen your symptoms. Following your treatment plan and avoiding flare ups can help slow the progression of your disease. Learn more at Lung.org/living-with-copd Educational materials were developed with support from AstraZeneca US . | America