I cough up clear mucus with light brown stuff in it. what is it? and why?

Need answers: Well, how much do you cough-up? When (more in the morning?)? What kind of cigarettes do you smoke? For how long have you smoked? Coughed? Is that light brown stuff ever red? Is the brown stuff in little spots or all smeared-up? Are you getting the impression I'm worried about your smoking? Besides that, it may just be irritation from air pollution, allergies, a mild cold or, oh yes, smoking.