depends how u smoke, if u take 30 bong hits and blow them all out into the room, each one wiht a smoking bowl, obviously will take more work to clear out the room. im not sure if your talking about this, or mayb hittin a few bowls from a pipe. however, heres a few guidelines to clear smell and prevent it

1.) use a doob tube
2.) cab the bowl after each hit
3.)blow out teh window, into a fan thats positioned on the windowsill, blowing outside
4.) use another fan that moves to keep new air moving
5.) use insence or a candle while smoking
6.) use ozium, or some kind of other air fresher before and after smoking

hope that helps.