My dad and my uncle used to make snow cream for us when we would all be at my grandparents house. It was so delicious. As usual we don't really measure things so the measurements are my best guesses.
Pan of Snow (no yellow snow, ha!)
1 teaspoonful of vanilla
1 cup of sugar
1/2 cup of milk
When you get the snow use a big pot to put it in like a pot you would use for stew or soup. Add the vanilla and about a cup full of sugar. Start with 1/2 cup of milk and add enough until you have the consistency of thick slush. Taste it and make sure it is sweet enough and then you will have your snow cream.
It was so yummy when I was young. My grandparents lived out in the country so we usually tried to use freshly fallen snow. I survived so I am pretty sure environmental toxins had not gotten into the snow yet. Try it - live a little!