The first thing to look for on an oxygen mask is whether it has a rubber or silicone seal, which will provide the best fit and prevent leakage.If you're flying in economy class, choose the masks that are located at your seat's headrest.If you're traveling as a family of four, make sure to get two masks with one child per adult.When using an oxygen tank during emergencies like fires or chemical spills, make sure there's enough air pressure left before handing it off to someone else.Remember that children under age four should never use an oxygen mask without assistance from their parents and caregivers.Make sure any medical equipment is out of reach of pets and small children who may not know better than to play with them.