can testify that some does go in your lungs from personal experience.
SWIM back when he was only snorting
heroin, ended up with a REALLY bad problem for a while. Some of the shit was
getting into his lungs, and he was highly allergic to whatever the cut was. Of course he wasn't stopping, so for about 2 weeks he could barely move 10 feet without becoming completely exhausted. His breaths were really shallow and wheezy, and he was constantly coughing shit up. That was during the worst, but he had lung problems for about 3 months.
He went to some clinic, and the doc
said his blood oxygen level was really low from it. He had actually told them about his heroin
use, but they didn't even think it was that and gave him some anti allergin rx and antibiotics. SWIM knows it was that, because the exact same thing happened to his brother, who went to this doctor that said he sees that all the time in heroin addicts.
It was probably because SWIM's tolerance was at his highest and he was needing to snort so much powder every day. SWIM solved it by switching over to injecting.