Why am I coughing grey sputum even if am not smoking? And what to do? -

Why am I coughing grey sputum even if am not smoking? And what to do? -

Sometimes I would cough tiny gel balls with grey streaks to think I have stopped smoking for years now, though, my environment most especially everytime I go home is not smoke-free with all the bus fumes (really black fumes!) and smokers around. Last check-up with chest x-ray (Feb.2008) is normal.sounds like phlegm. no biggie. its gross i know but you-re fine. the poor environment combined with natural congestion

Why am I coughing grey sputum even if am not smoking? And what to do? -