The person closest to a risk may have the least authority to stop the activity creating it.

The person nearest the danger usually has the least power to stop it. They can see the problem clearly and cannot halt the work, because stopping requires authority that sits with someone further away and less informed. This gap between knowledge and power is where most preventable accidents live.

If you hold authority anywhere, give the people closest to the work a real ability to stop it, and make sure using it costs them nothing. If you do not hold it, find the person who does and put your observation in writing. Neither is a guarantee, and both are considerably better than assuming somebody else has noticed.