Ah. I have a current AHA BLS cert. My understanding is, do breathing if you think there is a clear airway, and you have the appropriate PPE depending on the fluids on/around the person's mouth, and either you are doing compressions because there is no pulse or there is a pulse but the person is not breathing on their own. If you do choose to do rescue breathing, it's important to watch for chest rise to ensure that you're not breathing into their stomach, which is ineffective and will induce vomiting if the person regains consciousness.

There is a decision tree there that some people may be uncomfortable with in an emergency.

I welcome corrections from people with better training than mine.