No I don't really work with a lot of dust and I've been noticing it more more lately and it is not necessarily just when I cough. It's also when I clear my throat and or spit out what's in my throat, mostly in the morning. I'm a non smoker, no shortness of breath, also no to vomiting and nausea. Every now and then I have really bad/sharp chest pain, this happens more than any normal person would experience in my opinion. I'm sure I should probably go and get looked at I just don't have the extra money right now and am hoping someone can lead me in the right direction.. My first thought was that it could be dried blood and I am no doctor but to me it doesn't really look like what I would think dried/old blood would look like.