Just a quick thing to add:

I was chatting with my friend who is a herp vet a couple weeks ago and he was telling my about one of his clients that would take her snake to the park by her house. One day she took him right after they had sprayed the lawn with something, within two days her snake died.

My advice; if you have to take your snake outside, make sure you know the lawn. If its not yours you can't be sure what is on it.