Sand Gnats..or Teeth With Wings!??

Good lord who would of thought something so tiny could pack such a pinch!!  We went up to base yesterday afternoon to let Savannah play on the playground and so I could try out my new camera and get some really cute pictures of her playing.  Well within like 5 min of being there I was covered in gnats!!!  It was horrible!!  We had to leave after only 20 min because I couldn't stand it anymore.  Poor Savannah was SO UPSET!!  She was having such a good time and she cried and pointed at the play ground the whole way back to the car...it broke my heart!!  I have got to find something that keeps those damn little pests from bitting us so we can play at the park!   Any suggestions!????