What really bothers me, is my daughters best friends mother smokes, therefore when she goes and stays there or plays there she is subjected to smoke.

I find this infuriating, as I have protected my daughter from breathing in smoke, passive smoking kills too , as we all know.
What to do in this situation,? I don't know, I cannot ban my daughter from seeing her best friend, but I just hate the thought of her young lungs being exposed to this in anyway.

Hopefully the mother does not smoke around them.
What would you do in my situation?