Increase in mucus and change in color
Written by: Anna Nicholson | Last reviewed: July 2015.
- American Thoracic Society / European Respiratory Society Task Force. Standards for the Diagnosis and Management of Patients with COPD [Internet]. New York: American Thoracic Society;2004 [updated 2005 September 8].
- National Heart, Lung, and Blood Institute. “What Are the Signs and Symptoms of COPD?” Available at: http://www.nhlbi.nih.gov/health/health-topics/topics/copd/signs [Accessed 2 February 2015.]