Saanich School District, near Victoria, B.C. leads Canada in creating the healthiest environment for school children.  It has banned WiFi in all elementary schools. The new policy is below:  

Saanich School District 63

Technology Policy re: WiFi Amended – April, 2011

    a. There will be no WiFi in elementary schools. 

     b.  In middle and secondary schools, managed WiFi environments may be in adult workplaces including staff rooms
          and offices as necessary.

     c. Middle schools will have up to 25% coverage of student areas (with the understanding of some signal spillover)
         with the locations to be determined in accordance with educational needs as described in IEPs and overall
         educational needs for the school as determined with staff and PAC.

     d. Secondary schools will have school-wide coverage.

     e. The IT department will be responsible for all WiFi installations and will ensure that all wireless access points are
          managed, commercial grade and localized as possible.

Click here for full policy