The National Alert Signal is the sounding of a siren to warn the population of an imminent danger. A test of the sirens is carried out every first Wednesday of the month at 12:00.
The National Alert Signal is sounded in the event of a major incident necessitating a lockdown, for example a toxic cloud, a nuclear accident, a storm or an attack…
It provides you with a warning so that you can take measures to protect yourself.
The signal is a modulated (rising and falling) tone, comprising three one-minute sequences with a five second gap between each sequence.
During the siren test every first Wednesday of the month, the National Alert Code is partially transmitted.
To learn about the security instructions to be followed in the event that the National Alert Signal is broadcast, see the National Security Alert factsheet .