Breath play is Edge play always. If you enjoy this type of edge play, always check with the DM's to let them know that you plan to play in this manner. It will save them possibly interrupting your scene to check on your bottom. In addition, some venues may not permit this type of play and its always better to check before you start a scene.
Breath play is always dangerous no matter how safe you think you are being. Precautions can and should be taken such as NEVER EVER play alone.
I found the following article and wanted to share it here in its entirety: Take Your Breath Away - Basics of Breath Play