The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nm.  In terms of frequency, this corresponds to a band in the vicinity of 430–770 THz.

Blue light has a wavelenght of 450–495 nm, a frequency of 606–668 THz and a photon energy of 2.50–2.75 eV.  This places it at the higher end of energies the human eye can detect.  

I'm sure we'll learn all sorts of other interesting facts during the session, but how it helps us rescue people is beyond me...