Dream of

I have this dream where i am with my two oousins one is 2 and the other is 16. we are walking and everything is normal we come to this highway wait for a clearing then cross. my two year old cousin runs off down this highway, we get to a point where there is this thick gray fog. i think its normal fog cars are on this highway and are passing us. my 16 year old cousin is behind me, whereas the two year old has run into the fog. i go in the fog to get him and instantly my breath is taken away i cant breathe, i hear my cousin telling me to come on but i tell her i cant and turn around to walk away. i wake up never knowing what happened to my two year old cousin or the 16 year old cousin.