The siren system sounds all over Sweden, on the first Monday of March, June, September and December at three o’clock on the dot. Its purpose is to inform the Swedish public of a direct, life-threatening danger such as a big fire, explosion or war.
According to Mats Oscarsson, spokesman for the Swedish Rescue Service Agency, Räddningsverket, the continuous testing is a direct consequence of the war and has been carried out since the Second World War.
“The alarm system is found in areas where more than 1,000 people live, places that would be interesting military targets,” explains Oscarsson.
Sweden’s integrated warning system consists of the outdoor siren backed up by messages sent by radio and television stations across Sweden. Hoarse Fredrik’s warning is made up of long and short blasts and lasts for a least two minutes, followed by a longer signal which indicates “hazard over”.
It sounds rather like the horn of a ship as it leaves port, which makes for a rather curious aural experience hundreds of miles inland.
According to the Swedish Rescue Services Agency regulations, the powerful horns should not be placed higher than ten metres from the ground; any lower and there would be a serious risk that the 140 decibel blast would perforate the eardrums of Swedes in the vicinity.
(By way of comparison, the sound level of a busy street is reaches 90 dB and a jet engine 30 metres away has a sound level of 150 dB.)
Since the war, a range of different warning systems have been tested in Sweden. Until 1961, air-raid sirens were tested to warn the public about potential air invasion. In 1968, the Civil Defence Committee decided that an alarm system would be tested four times a year and in 1984, the warning system was modified to what it is today.
But have Swedes become so used to the warning that it would be ineffective? There has not been a survey about how the public reacts to the warnings since the beginning of the 1990s, but Mats Oscarsson says the reactions documented in the last report varied greatly.
“Some people did exactly what they were supposed to do, which is to go inside, lock the doors, shut-down the ventilation system and turn on the radio,” he said.
“Others just looked up and then continued on with their business. I do hope that if a warning came on any other day other than Monday at three o’clock, people would react accordingly. It could be a matter of life or death,” says Oscarsson.
There are about 4,500 signal horns all over Sweden. They are owned by the state but maintained by local authorities.
Stockholm alone spent 1.2 million kronor this year maintaining the 300 horns in the city, according to Göran Arredal from Stockholm’s Fire Department. Arredal told The Local that the system, once created in times of war, is now used for other purposes and can still be very useful.
“The war-threat is now seen as basically non-existent, but there are others threats that we should warn the public about. For example, fires, gas leakages, explosions and floods,” he said.
Although it has never been used in Stockholm, he remembers that it did sound once a few years back in Uppsala, when the telephone lines went down. What is important is to remember to turn on the radio or television, he explains.
“The signal in itself does not do much, it only tells people that something is happening. If the alarm went off on any other day of the week, people would probably start wondering. Hopefully, they remember to turn on their radios or television,” says Arredal.
So if it is not Monday and you hear a sound like an ocean liner docking in the street outside – be alarmed. And if a foreign army decides to invade on the first Monday of March, June, September or December, they may find Swedes curiously unresponsive.