Could you maybe show them this:
How to protect children from second-hand smoke, third-hand smoke and vapour
The most important way to protect your child from second-hand smoke, third-hand smoke and vapour is to quit smoking or vaping and to support other adults in your child’s life to quit.
This reduces your child’s exposure to second-hand smoke, third-hand smoke and vapour. It also gives your child positive non-smoking and non-vaping role models.
If you’re not quite ready to quit, or if someone else in your home smokes or vapes, there are still things you can do to reduce your child’s exposure to the smoke or vapour.
One of the most important things is to make sure no-one smokes or vapes near your child in your house. This means you’ll have to smoke or vape away from your child, and you’ll need to ask other family members, friends, carers and visitors to do the same. Also make sure no-one ever smokes or vapes in an enclosed area near your child.
You might need to explain to friends and family that simply blowing smoke or vapour away from your child doesn’t protect your child from the harmful effects of smoke or vapour. You could say that you want to keep your child healthy by minimising their exposure to smoke or vapour.
When visiting friends or leaving children in someone else’s care, try to make sure the environment is free of smoke and vapour.
I found it simply by Googling, how does vaping affect young children around me.