I won't go into the official diagnosis stuff, but firstly it is a disorder characterized by fear. That means the triggers are those that cause automatic thoughts led by memories. The highest rate of frequency over the last 15+ years is at home, yet I do not experience them as much since about then. I finally entered therapy on a journey of learning. Where is not a trigger for me it is when something else may be occurring that it has a higher likelihood of happening. Circumstances lends toward being a possibility.
In other words I have more than one diagnosis to consider like PTSD and an experience with two forms of amnesia known in the world of psychology as dissociation. A thought to remember is panic attacks is very closely related to PTSD.
With my experience the amnesia is a result of a horrific car crash in '78. So, at one time seeing a Volkswagen bug about the same year as the one I drove could trigger a panic attack. Seems odd I am sure. When seeing it the automatic thoughts led to envisioning my crumpled car and recollection of the experienced amnesia, which is unique itself. Sometimes witnessing a car crash on TV could be a trigger or hearing the loud crunch of one in real life.
Another is awakening from sleep with one of those mysterious and mystical can't be figured out dreams. So, in that particular case where is where I would be sleeping or napping. When was even in the afternoon contrast at night.