Some info here is about UK warning system, so unless you are in the UK, disregard that.   https://www.the-sun.com/news/211684/world-war-3-ww3-nuclear-attack-how-to-prepare-apocalypse/ Experts recommend you follow the guidelines below to protect yourself, your family and your home - if you believe an attack is imminent. Build an Emergency Supply Kit, which includes items like non-perishable food, water, a battery-powered or hand-crank radio, extra flashlights and batteries. You may want to prepare a kit for your workplace and a portable kit to keep in your car in case you are told to evacuate. Make a Family Emergency Plan. Your family may not be together when disaster strikes, so it is important to know how you will contact one another, how you will get back together and what you will do in case of an emergency. Find out from officials if any public buildings in your community have been designated as fallout shelters. If none have been designated, make your own list of potential shelters. These places would include basements or the windowless central area of middle floors in high-rise buildings.   What should you have in your survival kit? It's suggested you go out and buy as many of these items as quickly as possible: Water filters Canned goods (stews, fruit, tuna, meats, etc) Ready-to-eat foods (granola, cheese, protein bars, etc) Medical kits Peanut butter What to do after a nuclear blast? Although Ukrainian protocol is unclear, it was previously reported that the UK Government was working on a new alert system to prepare Brits for the horror of a nuclear war. Back in the dark days of the Cold War, the British government developed a “four-minute warning” system to alert the public that the country had come under attack. The warning system, which was in place from 1953-1992, used air raid sirens, TV bulletins and radio broadcasts to spread the terrifying news but, thankfully, it was never used. In 2003, the National Attack Warning System (NAWS) was developed, allowing the government to warn the population by phone, radio and TV if we ever come under attack. Nowadays nuclear bomb alert text messages and social media are the preferred method. Decay rates of the radioactive fallout are the same for any size nuclear device. However, the amount of fallout will vary based on the size of the device and its proximity to the ground. Therefore, it might be necessary for those in the areas with highest radiation levels to shelter for up to a month. The heaviest fallout would be limited to the area at or downwind from the explosion and 80 per cent of the fallout would occur during the first 24 hours. People in most of the areas that would be affected could be allowed to come out of shelter within a few days and, if necessary, evacuate to unaffected areas. Keep listening to the radio and television for news about what to do, where to go and places to avoid. Stay away from damaged areas. Stay away from areas marked "radiation hazard" or "HAZMAT". Remember that radiation cannot be seen, smelled or otherwise detected by human senses. Assorted drink mixes, if you have children with you Multi-vitamins Iodine solution, hydrogen peroxide, alcohol, painkillers Dried milk Largest bags of rice, beans, flour, oats, sugar and honey Gallons of cooking oil Baking powder & baking soda & spice assortment pack A manual can opener Kitchen matches and disposable lighters Sanitary napkins and diapers, if needed Flashlights (ideally LED) and portable radios, if you don't already have them Plenty more batteries, at least three sets, for each of the above Bottled water (especially if home supplies not secured yet) Baby wipes Bleach Fire extinguisher Paper or plastic plates/cups/utensils Cheap plastic hooded rain ponchos What to do during a nuclear blast? The following are guidelines for what to do in the event of a nuclear explosion. Listen for official information via online, radio or TV and follow the instructions provided by emergency response personnel. If an attack warning is issued, take cover as quickly as you can, below ground if possible, and stay there until instructed to do otherwise. Find the nearest building, preferably built of brick or concrete, and go inside to avoid any radioactive material outside. If better shelter, such as a multi-storey building or basement can be reached within a few minutes, go there immediately. Go as far below ground as possible or in the centre of a tall building. The goal is to put as many walls and as much concrete, brick and soil between you and the radioactive material outside. Expect to stay inside for at least 24 hours unless told otherwise by authorities. What to do if you are caught outside during a nuclear blast? Do not look at the flash or fireball - it can blind you. Take cover behind anything that might offer protection. Lie flat on the ground and cover your head. If the explosion is some distance away, it could take 30 seconds or more for the blast wave to hit. Take shelter as soon as you can, even if you are many miles from ground zero where the attack occurred - radioactive fallout can be carried by the winds for hundreds of miles. If you were outside during or after the blast, get clean as soon as possible, to remove radioactive material that may have settled on your body. Remove your clothing to keep radioactive material from spreading. Removing the outer layer of clothing can remove up to 90% of radioactive material. If practical, place your contaminated clothing in a plastic bag and seal or tie the bag. When possible, take a shower with lots of soap and water to help remove radioactive contamination. Do not scrub or scratch the skin. Wash your hair with shampoo or soap and water. Do not use conditioner in your hair because it will bind radioactive material to your hair, keeping it from rinsing out easily.