I live with my mom, my 23 yr old brother, his 18 yr old girlfriend and my 12 yr old brother. I am 19 yrs old and I recently discovered my older brother has been smoking in my house. I asked him to stop but it seems to mean nothing to him. We got into a huge argument because I am worried about my younger brother being exposed to drugs. So far he has only done it when my younger brother wasn't home. My mom won't do anything about it.. What should I do?