Hydrogen vs. Battery Electric Cars

Physics Girl: PLEASE ANSWER THIS QUESTION. If hydrogen, because the molecules are so light and small (which means means that hydrogen LEAKS and FLOATS UPWARD much faster than all other gases)--doesn't that imply the danger that we will eventually run of hydrogen because it escapes into space? I have a chemistry degree and know that a little knowledge is a dangerous thing, but I can't get this idea out of my head.