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The Community Warning System safety sirens are tested on the first Wednesday of every month at 11:00 a.m. in industrial areas of East, West, and Central Contra Costa- County. In the event of a real emergency, safety sirens in the affected areas will be sounded to alert you to "shelter-in-place" and turn on your radio or television for information.

To "shelter-in-place":

  • Go inside
  • Shut all doors, close and lock all windows
  • Turn on your radio or TV for further instructions
  • Don't use your phone unless there is a life-threatening emergency
  • After the shelter-in-place alert is over, open your windows and doors and air out your house

For more information about the Community Warning System, call (925) 313-9296.