A box fan will work if it is directly in front of the open window and placed on the workbench in front of the torch ( several feet away of course.
Then you need replacement air such as an open window or door behind you. It is adequate at best and will do for a start if you do not have any symptoms after torching. headaches, chest hurts, shallow breathing, dizzyness blurriness etc.
Here is a long thread from Wetcanvas and it has oodles of pictures of peeps work stations. Enjoy! Most of them inadequate or down right illegal!
http://www.wetcanvas.com/forums/showthread.php?t=93005