If you want to specify an explosion proof switch then as per IEC you can specify Exd or Exde.
You can aslo add the gas groop environment ie IIA/B/C and the temp rating say T3 and finally the ingress protection (IP) rating of say IP56 for general outdoor application.So adding everything together the total spec for the switch would read
Exd,IIB,T3,IP56 or Exde,IIB,T3,IP56
Note that an Exd switch will cost more as it will have a metal housing but will be more rugged too, while Exde will be relatively cheaper as it will have a plastic (GRP) housing but not usually specified for rugged duty.
Finally, it is not permissible (by IEC) to use or specify Exd or Exde devices in zone 0 where only Exs ( s being - special design) would be permitted for power application devices.