1. Black sputum in the morning may be due to air pollution, if you drive a lot, have any occupational or environmental exposure to sources of smoke, irritant fumes, chemicals or hazardous materials.
2. Get a Chest X-ray PA view done.
3. Get your sputum examined for the presence of fungus or dried blood.
4. Lung Function Test will be useful if you are now developing symptoms.
5. Is your phlegm increasing? This may signify chronic bronchitis