Define "outside". Is it out in the open or under a tent? Temporary or permanent? BBQ or what? Professional or private?
In all cases I have never heard of a hood BUT instructions for the equipment being used as well as common sense should be followed. It's not a good idea to grill burgers and steaks under a tent that will fill with smoke and choke your guests. If this is a professional gig, the fire or building department will want to look around see that you have proper fire extinguishers etc.