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What to do if there is a nuclear alert

Official updatesLU-Alert · RTL, 100.7 · 112

Do this now

  1. Go inside the nearest solid building and stay there. Clothes and cars do not protect you from radiation; walls do.
  2. Close the doors, windows and shutters. Switch off ventilation, heating and air conditioning, and shut off any rainwater system that feeds the house.
  3. Stay in a room away from doors and windows. The current official advice is that you do not need to go down to the cellar.
  4. Switch on the radio, Status: Verified, and watch for LU-Alert messages. The authorities say which zones must shelter, take iodine or leave, and for how long.
  5. Take iodine tablets only when the authorities say so, and follow the dose on the leaflet in the box. The tablets protect only the thyroid and work only if the timing is right, so wait for the instruction. Never go outside to look for tablets.
  6. If you came in from outside, take off your outer clothes and shoes at the door, put them in a bag, and shower, hair first. Wash pets before you let them in.
  7. Leave the children where they are: schools, crèches and care homes are sheltered or evacuated by the authorities. Call Status: Verified only if someone is hurt, and keep other calls short.

Before

How warnings reach you

  • In a nuclear alert, sirens sound in the threatened zones, and LU-Alert sends cell broadcast messages, SMS and app alerts. The radio carries the instructions. Learn the signals on Alerts and sirens, and what to do when one sounds on Siren is sounding.

Have the tablets at home

  • Iodine tablets have been distributed to households in Luxembourg. If you have none, ask your municipal administration: it hands them out to residents.
  • Official pages differ on who should take the tablets. Ask your commune or your doctor now, not during an alert, and check the expiry date on the box.
  • If you have a thyroid condition or know that you react to iodine, talk to your doctor about the tablets before you ever need them.

Prepare to stay in for a day or more

  • Plan to stay inside for at least Status: Verified hours. The Luxembourg plan says sheltering normally lasts no more than Status: Verified hours.
  • Stock water, Status: Verified per person per day for Status: Verified, and food you can eat without cooking. See the emergency kit checklist.
  • Keep wide tape in the kit to seal gaps around windows and vents, and learn now how to switch off the ventilation at home and at work.
  • Keep the car at least Status: Verified full and a grab bag ready, in case the authorities order an evacuation. See Leaving home.
  • If you have a vegetable patch and there is time, cover it with plastic sheeting.

Older documents say

The infocrise "Taking shelter" page (last updated June 2020) and the 2014 nuclear brochure say to prefer the lower rooms of the house, including the cellar. The infocrise nuclear FAQ, updated in October 2026, says there is no need to go down to the cellar or up to the attic: stay inside, away from doors and windows. The newer FAQ takes precedence. A windowless cellar room is not wrong if you have one; what matters is staying indoors with the windows shut.

After

  • Come out only after the end-of-alarm signal or an official message. Air the house when you are told it is safe.
  • Eat tinned, dried, frozen or stored food, or fresh food from regions that were not affected. Do not eat anything from your own garden until the authorities say you can. Tap water stays safe unless they say otherwise.
  • For as long as the advice lasts, limit your time outside, especially in the rain. Change your clothes after each time out, and keep the pets in where you can.
  • Restock what you used, and replace iodine tablets that were taken or have expired.
  • Feeling anxious for a while after an alert is common. Talk about it with people close to you, and ask for help if it does not ease.

If you are…

Looking after children

  • Do not drive to the school or crèche. Children there are sheltered, given tablets or evacuated by the authorities, with the same instructions you hear on the radio.
  • The dose differs for infants, children and adults. Give tablets only when the instruction comes, and follow the leaflet for each age.
  • Say what is happening in plain words: we stay inside, we keep the windows shut, we listen to the radio.

Older, ill, or living with a disability

  • If you could not shelter or leave on your own, phone your municipal administration now so that help is planned before an alert.
  • Keep your medicines for at least Status: Verified within reach, with the chargers for any equipment you depend on.

With pets

  • Keep them inside with you for the whole alert. Wash them before you let them back in, and keep their food and water indoors.

In a flat above the third floor

  • You do not need to go down. Choose an inner room or the hallway, away from the windows, and keep the windows shut even if it gets warm.

Easy-read summary

  • Go inside and stay inside.
  • Close the windows and switch off the ventilation.
  • Listen to the radio for instructions.
  • Take iodine tablets only when the authorities say so.
  • Take off your outer clothes and have a shower.