Cigarette Smokers And The Brown Oysters

What is the composition of the brown phlegm I (and other fellow longtime smokers) spew every morning during my steamy coughing fit in the shower (steam apparently loosens the material for oral rejection)?

Is that accumulated tar my lungs are ridding myself of, or what? It’s nasty, I know, I want to quit smoking and have smoked for 20 years now and I’m only 38…has there been scientific analysis of this lung matter?

No idea about the composition, but I believe the official term is “Lung Chunks”.'s_cough Perhaps