Hello Tyler, Most of our efforts to deal with lung problems to do with smoking are aimed at people who have developed symptoms (like a cough for instance). Before this the most important thing to do is to stop smoking. If you stop smoking your body recovers remarkably quickly and you don’t have to worry about getting tar/other bad chemicals out.
If you don’t stop smoking, even if you could develop a tar-remover it would be a never-ending task and I don’t think you would stop problems developing.
There are now drug-treatments as well as nicotine supplements that make stopping smoking easier (see bupropion and varenicline).
You make an interesting suggestion with your tar-removing strategy. I don’t think we have any treatments for people who smoke to try and prevent them damaging themselves. I’m afraid you wouldn’t get funding to investigate this as people would say that stopping smoking is effective.
Try not to be too hard on your dad it is a very difficult habit to beat. The most important thing is to keep trying to stop because every time you try you are more likely to succeed…All the best to you and your dad.