I won't give a balloon to a kid under 3. I explain to the parents why, and if they insist - I give the parents a balloon and let them know they can do with it what they want. I warn them of all the dangers and ask that they take care with the balloon and child (eating, bouncing, etc)..
I've seen parents later in the day at festivals letting their kids put balloons in their mouths and have stopped what I'm doing to stiltwalk over to them to give them another warning. Thus far, the second warning has been sufficient to where I've not had to take a balloon away from someone...
I have a sign stating the hazards of balloons at my station. When roving or just dropping balloons off at random; I attach a card to the balloon...
adding card image below
