Facial tissues are not designed to break apart the way that toilet paper is. (I’m sure you’ve tried blowing your nose on the latter–remember the way it shreds?) In an emergency situation, I treat them like tampons–if I’m asked to dispose of those in a wastebin, I do the same with anything else that isn’t toilet paper or bodily wastes. Otherwise, I tear it in half (lengthwise) before I use it.