Found this info on a quick search * * Nationwide emergency and road information calling. Nationally recognized coded squelch for 462.675 emergency simplex and repeater operation is 141.3Hz.Unless you know you have access to a repeater on this frequency pair, do not expect this channel to be of any practical use in emergencies. Low power simplex portables on 462.675 will not attract much attention. A cell phone is much more reliable.
I also found this >> There is a push to have the FRS channel 1 (462.5625) with no tone to be used as the emergency channel. You can check this also www.marscan.com