The enquirers local school displays a sign on the main gate advising parents that the use of mobile phones on site is banned for reasons of health and safety. The enquirer would be happy to accept a simple school policy ruling and felt that health and safety was being used as a poor excuse.
There are a number of possible reasons why a school might decide to ban the use of mobile phones - although any connection with 'health and safety' is tenuous. Choosing to explain its policy in this way via a sign on the school gate does nothing to help pupils and parents understand the reason(s) for the ban in this school. It would be better for all concerned if the specific reason for the school's policy was made clear rather than use health and safety as an excuse.