The sirens in Denmark are electronic and computer-controlled.

Once every year - on the first Wednesday of May - the sirens are tested.

Signal 1- Go indoors

The tone will rise quickly and fall again slowly. The signal lasts for 45 seconds.

When you hear the signal:

• Go indoors
• Close doors, windows and ventilation systems
• Make sure that the people around you know how to react

Listen to the radio, watch TV (DR or TV2). Here you will be told what to do - for example, in connection with a nuclear incident, chemical release, or flood.

Signal 2 - Danger is over

One long tone lasting 45 seconds.

When you hear the signal:

• You may now leave the indoor protection
• You can return to your daily chores

Sirens are installed in areas having more than 1,000 inhabitants.

Here the alarm will be sounded by mobile sirens mounted on police cars.