My policy and the school I work in, is, that they should wear Safety Glasses at all times when in the workshop. The only time I don’t worry is if the whole class is in the shop but doing theory. Students do unpredictable thing and I use the real example of what happened to a student of mine many years ago.
Two friend were in the painting area and one flicked a small paint brush at her friend and pocked her in the eye. The student had to go to hospital and could have lost her eye.
Policing is just part of the conversation as I go around the workshop/class. I sometimes give rewards to students who do the right thing.
You could also make a Class Challenge out of it. Graph the week and reward the class which works together to “Think Safety”
Hope that’s of some help.