Why does the sputum contain blackish particles?

Q: For the the last 6 months whenever I take deep cough, my sputum contains blackish particles. I do not have fever or fatigue. When I speak continuously for 5-6 minutes sputum collects in my throat. What is this due to and should I get my sputum cultured?

A:If one is exposed to dusty or polluted environment then this may be coughed out in sputum. Even smoking, both active or passive, can cause this. Try avoiding all this and, if it still persists, get examined by an ENT specialist.