Partial pressuew
I interpret this to say that if the air pressure was much higher, but the concentration of O2 was about the same, the fire hazard would be about the same as it is in our atmosphere. But would animal metabolisms be accelerated?
However, the higher N2 level (concentration being the same) might lead to Nitrogen Narcosis (Rapture of the Deep). Rapture is not the same as compression sickness, "the bends", but divers are trained to be aware of it. It leads to erratic behavior and impaired mental performance. IOW, the rapture may not kill you, but it can cause you to do something stupid which will.
Still, I suppose evolution could provide a mechanism to deal with it in terrestrial animals.