Blue is the only color that volunteer firefighters and rescue personal are permitted to use in PA, unless you are brass (chief, asistant chief, etc.).
When I used to run, I didn't bother with the blue lights. As soon as the state police would spot a "blue lighter" coming, they would hit them with radar. Several folks got pegged for speeding tickets on the way to calls. My stealth theory worked and I was never pulled when responding.
