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Hell, some call it the Phantom Death, 'cause that's what it is. You can't see it, you can't hear it, you can't even smell it. It basically builds up in your system. You never feel it until it's too late. The more trips you make to Hot Spots, the more it builds up and it will never leave your system. Ever. The Rads just keep building up. Well... unless you can get a hold of some Rad-Away.

Jake, Fallout

Radiation is the chief delayed effect of a nuclear explosion. It has long lifetimes (half-lives ranging from days to millennia). The primary source of these products is the debris left from fission reactions. A potentially significant secondary source is neutron capture by non-radioactive isotopes both within the bomb and in the outside environment. Radiation is a very important element in Fallout and is also considered to be an innovative feature throughout the games of the series.

Nature of radiation[edit | edit source]

Short-lived isotopes release their decay energy rapidly, creating intense radiation fields that also decline quickly. Long-lived isotopes release energy over long periods of time, creating radiation that is much less intense but more persistent. Fission products thus initially have a very high level of radiation that declines quickly, but as the intensity of radiation drops, so does the rate of decline.


These radioactive products are most hazardous when they settle to the ground as fallout. The rate at which fallout settles depends very strongly on the altitude at which the explosion occurs, and to a lesser extent on the size of the explosion. If the explosion is a true air-burst (the fireball does not touch the ground), when the vaporized radioactive products cool enough to condense and solidify, they will do so to form microscopic particles. These particles are mostly lifted high into the atmosphere by the rising fireball, although significant amounts are deposited in the lower atmosphere by mixing that occurs due to convective circulation within the fireball. The larger the explosion, the higher and faster the fallout is lofted, and the smaller the proportion that is deposited in the lower atmosphere. For explosions with yields of 100kT or less, the fireball does not rise above the troposphere where precipitation occurs. All of this fallout will thus be brought to the ground by weather processes within months at most (usually much faster). In the megaton range, the fireball rises so high that it enters the stratosphere. The stratosphere is dry, and no weather processes exist there to bring fallout down quickly. Small fallout particles will descend over a period of months or years. Such long-delayed fallout has lost most of its hazard by the time it comes down, and will be distributed on a global scale. As yields increase above 100kT, progressively more and more of the total fallout is injected into the stratosphere.


An explosion closer to the ground (close enough for the fireball to touch) sucks large amounts of dirt into the fireball. The dirt usually does not vaporize, and if it does, there is so much of it that it forms large particles. The radioactive isotopes are deposited on soil particles, which can fall quickly to earth. Fallout is deposited over a time span of minutes to days, creating downwind contamination both nearby and thousands of kilometers away. The most intense radiation is created by nearby fallout, because it is more densely deposited, and because short-lived isotopes haven't decayed yet. Weather conditions can affect this considerably of course. In particular, rainfall can "rain out" fallout to create very intense localized concentrations. Both external exposure to penetrating radiation, and internal exposure (ingestion of radioactive material) pose serious health risks. Explosions close to the ground that do not touch it can still generate substantial hazards immediately below the burst point by neutron-activation. Neutrons absorbed by the soil can generate considerable radiation for several hours.

Measurement[edit | edit source]

What do you need a Gieger counter for!? [Laughs] Though it's been 80 years or so since the bombs fell, there's still radiation around, you goof. You can't see it, never could, but it's there. Heck I'm willin' to bet you got some counts on you now. Everyone that lives in the wastes has a few RAD counts.


A rad is a unit of measurement used to measure the level of radiation in an area. When Vault-Tec Industries created their vaults they equipped them with sensors that could detect radiation levels. This measurement is reported to the residents over the public announcement system.

In Vault 101 on July 13, 2268, the public announcement system reported the level of radiation -- "Current radiation level - 0 rads, as always."

In our world, the rad is a real unit, being equal to 0.01 Joules per kilogram (1 rad means 0.01 Joules of radiation was absorbed by 1 kilogram of matter), meaning radiation absorbed dose.

Mutations[edit | edit source]

Ghoul D.jpg

The various types of mutant creatures that inhabit the wastelands were mostly caused by radiation. Mutations in these creatures may have been caused by exposure to radiation from atomic bomb explosions themselves. Because ionizing radiation (the main type of radiation from an atomic explosion) consists of very energetic photons, it is capable of detaching electrons from molecules and atoms. This makes ionizing radiation extremely dangerous for living organisms because they can alter the creature's DNA, causing mutations i.e. tissues and organs do not grow normally. It is more likely their mutations were caused by the radioactive particles released by these explosions however. Radioactive isotopes in the environment (i.e. fallout) can cause mutations if they are taken into an organism's body. For example, if a mammal ingested Ca-45, an unstable isotope of calcium, the body would regard it as normal calcium and deposit it in the creature's bones. Its accumulation there often leads to bone cancer.

This is where giant ants, geckos, spore plants, radscorpions, brahmin, and the various mutant rodent species come from. Also, this is how ghouls- decrepit, ragged, almost rotting, zombie-like victims of massive radiation poisoning- are made. In Fallout 1, most of the ghoul population was created from vault dwellers living in Vault 12 under the city of Bakersfield (better known as the Necropolis after the War). As part of the vast Vault Experiment Program, the Vault 12 vault door was designed not to close properly. Thus, massive amounts of radiation leaked in affecting those within the vault, most of whom were turned into the current ghoul population. Generally, in the Fallout universe, massive exposure to radiation causes humans to die, however prolonged exposure seems to be capable of transforming people into ghouls. Also, all ghouls are completely sterile. There is only one generation of ghouls in the Wasteland and it is the last. Furthermore, the ghoul transformation grants its subjects extremely long lives. Ghouls created in the Great War of 2077 were still alive in 2287. Ghouls are generally as intelligent as normal humans, though some may lose their intelligence over time and turn feral. However, their extreme ugliness and physical frailty makes the life of a ghoul difficult at best. Ghouls are naturally immune to radiation, and, in fact, are also healed by it.

Nonetheless, this fact was of little consequence to pre-War society (as you get to know in Fallout 3, Fallout: New Vegas, Fallout 4, and Fallout 76): from automobile propulsion to moon rockets, fission batteries to a type of cola that glows in the dark, radioactive substances were used for almost any purpose, and people accepted the inevitable radiation exposure as a by-product of the immense benefits nuclear products brought to their lives. Even after "the bombs fell", the inhabitants of the "Wasteland" have no repulsion towards radioactivity: For instance, the settlement named "Megaton" is built around an undetonated atomic bomb, which is even worshiped by some people in the Children of Atom cult. A sect of the Children of Atom also worship a large radioactive mass known as "The Fog".

Radiation in the Fallout World[edit | edit source]

Much of the pre-War Fallout world revolved around the use of radiation. From fission cars to using radiation in soft drinks, most of the world was comfortable with the persistent effects of radiation in their daily lives. This may account for large quantities of RadAway and Rad-X that can be found in the Fallout Universe, being used for common treatment of radiation poisoning among citizens.

Generally, the primary source of exposure to radiation is via irradiated food and drink. Most water sources, especially prior to the activation of Project Purity, are irradiated. Various water sources will differ in the concentration of radiation and drinking from an irradiated source will always be more hazardous than coming into contact with the water.

Craters left by nuclear warheads are also usually areas of highly concentrated radiation, such as outside Vault 87 in Fallout 3 or at Black Mountain in Fallout: New Vegas.

Another primary source of radiation is from toxic waste dumped pre-War. These brown and white barrels can often be found in various locations, usually emitting low to medium levels of radiation in a close vicinity. Areas emitting higher levels in wider areas can be found at larger dump sites throughout the Fallout universe. Despite our real-world restrictions preventing the dumping of toxic waste, despite protests, the pre-War Fallout universe seemed to have no such restrictions and dumping was not uncommon due to the high yields of toxic waste created from various forms of production and experiments. In Fallout: New Vegas at the REPCONN headquarters, during the visitor tour of the facility you can read several information plaques that mention their dumping of toxic waste (and even being allowed to place waste inside certain government-backed public schools) and its (believed) apparent harmless effects.

Radiation poisoning in-game[edit | edit source]

Fallout, Fallout 2, Fallout Tactics[edit | edit source]

The following section is transcluded from Radiated. To modify, please edit the source page.
0-149 very nauseous
150-299 slightly fatigued -1
300-449 vomiting does not stop -3 -1 -1
450-599 hair is falling out -5 -5 -2 -1 -2
600-999 skin is falling off -10 -15 -4 -3 -3 -3 -1 -5
1000+ intense agony -10 -20 -6 -5 -5 -5 -3 -6

The character has a hidden radiation ("Rad") count that can be checked with a Geiger counter. This rad count causes the effect "radiated" to appear. As the Geiger count increases, further radiation poisoning occurs. Merely being "radiated" incurs no penalty. If the rad count gets high enough, however, SPECIAL stats begin to drop, and if any of these drop to zero due to poisoning, the character dies. Also, should the character be able to survive to maximum irradiation (1000 rads) (as in their stats do not reach zero), the character has 24 hours to use enough rad-aways to get themselves under 1000 rads or die anyway.

Notes[edit | edit source]

Fallout 3[edit | edit source]

Rads Level Effect
0-199 No Effect
200-399 Minor Radiation Poisoning -1 END
400-599 Advanced Radiation Poisoning -2 END, -1 AGL
600-799 Critical Radiation Poisoning -3 END, -2 AGL, -1 STR
800-999 Deadly Radiation Poisoning -3 END, -2 AGL, -2 STR
1000+ Fatal Radiation Poisoning DEATH (HP: -10,000)

Eating and drinking most food items or entering an irradiated zone causes the player to gain rads. The player loses S.P.E.C.I.A.L. attributes at certain thresholds, and dies at 1000 rads. Radiation does not directly affect your hit points, however, through penalties affecting Endurance, the player's Max health may be lowered.

The Pip-Boy 3000's dosimeter will appear in the upper right whenever you are exposed. There are five major ticks (200, 400, 600, 800, and 1000 rads), with minor ticks at multiples of 66.67, e.g., 67, 133, 200, 267, 333, 400, etc. You can also check your rad status in your Pip-Boy to see your rad resistance and rad level.

There is also a dial in the upper-left of your Pip-Boy that shows the approximate radiation level. This meter is difficult to read however, due to the needle's constant movement.

Rad exposure is usually limited; only very rarely will zones be so irradiated that venturing into them results in a quick death. You have to stand in +1 rad water for a long time to die (16 minutes and 40 seconds), and more generally, you can splash briefly through radioactive water dozens of times before you reach the barely-annoying 200 rad threshold.

The quickest way to die of massive exposure is near the surface entrance to Vault 87, where radiation can reach up to 3,932 rads per second. (It's possible to reach the entrance by frequently pausing to use RadAway, but you need tons of it.) Jumping into the river off the Pitt Bridge is the second quickest way, reaching upwards of 600 rads a second. Trying to enter the G.E.C.K. chamber of Vault 87 is the third quickest way. Although it starts at 1 rad per second, it virtually doubles every couple of seconds, until you're receiving about 400 rads per second. Also, if you use the save-before-you-fall glitch, the mouth of the blast furnace in the Steelyard is upward of 400 rads a second.

Rads can be flushed by:

Radiation can be resisted by equipping certain types of apparel, such as radiation suits or power armor. A dose of the chem Rad-X also grants the player a radiation resistance based on his or her Medicine skill, but the effects do not stack. This resistance is applied to all sources of radiation, from the external environment to irradiated consumables.

The Lead Belly perk halves the rads you take from any irradiated water you drink while the Rad Resistance and Cyborg perks raise your overall radiation resistance. Also, if you complete the 'contract radiation sickness' part of The Wasteland Survival Guide with a reading of 600 rads or more (the optional objective), you gain the Rad Regeneration perk.

In Fallout 3, all non-player characters are immune to radiation. This explains why non-player characters like Confessor Cromwell (who stands in irradiated water at almost all times) don't die from radiation poisoning. Certain enemies, such as glowing ones or centaurs, have radiation-based attacks that can increase the player's rads.

Fallout: New Vegas[edit | edit source]

Fallout: New Vegas uses the same radiation mechanics as Fallout 3, keeping some perks, such as Lead Belly, Rad Resistance and Rad Absorption, while adding a new perk, Rad Child.

You can remove radiation poisoning by using RadAway, see a doctor, or by using the auto-doc in Big Mt's Sink. The Irradiated Beauty perk in Lonesome Road removes rads while sleeping.

Fallout 4[edit | edit source]

Unlike in previous titles, accumulating radiation in Fallout 4 does not reduce SPECIAL statistics. Rather, it ticks away on the health bar, lowering one's maximum health; therefore, the more radiation one accumulates, the lesser one's health. As in Fallout 3 and Fallout: New Vegas, the maximum number of rads one can take before dying from hit point loss is 1000.

Several perks, such as Lead Belly, Aquaboy, and Rad Resistant are dedicated to reducing the amount of radiation taken. Additionally, several pieces of armor can be modified to improve radiation resistance.

Highly irradiated zones[edit | edit source]

The more trips you make to Hot Spots, the more it builds up and it will never leave your system. Ever. The Rads just keep building up.

Jake, Fallout

Fallout[edit | edit source]

  • The Glow, with instant death awaiting any who venture without lots of Rad-X and RadAway.

Fallout 2[edit | edit source]

Fallout 3[edit | edit source]

All numbers assume no protection.

Fallout: New Vegas[edit | edit source]

  • Ground zero at Dry Wells gets up to 102 rads/second. Lonesome RoadGametitle-FNV LR.png
  • Camp Searchlight, with as much as 28 rads per second in the town center.
  • The shack in the Old nuclear test site peaks at 20 rads/second.
  • Jack Rabbit springs, a place crawling with centaurs and hot springs peaking at 10 rads per second when swimming.
  • Cottonwood Crater is a nuclear impact site, located South of Cottonwood Cove. It has a pool of irradiated water in the middle, with golden geckos walking around. Beware of high radiation levels, peaking at 7 rads per second.
  • Crescent Canyon East/Crescent Canyon West, with barrels of radioactive material lying around. This area has a maximum of 5-6 rads per second.
  • Vault 34 contains constant background radiation (+1), reaching up to +5 in the lower levels and +13 by the barrels in the cave entrance.
  • The Devil's Throat, 6+ near the barrels and water
  • Around and near Black Mountain, +4 near the crater and dying off near there.
  • Cottonwood Cove, if the player releases the radioactive barrels the exterior camp will become irradiated, though interior areas will not.
  • Mesquite Mountains Crater
  • Powder Ganger Camp West, located near here (left at the Corvega billboard when heading south) is a puddle with many toxic barrels producing 3 rads/sec at its peak.
  • Poseidon Gas Station is covered in toxic barrels, peaking at about +2 rads.
  • South of Poseidon Gas Station there is a large patch of toxic barrels and irradiated mud.

Fallout 4[edit | edit source]

Notes[edit | edit source]

  • In Fallout 3 nearly any puddle of filth-infested liquid will contain at least some rads per second, however, most of these similar puddles in Fallout New Vegas do not contain any rads whatsoever.
  • If for any reason, going to your Pip-Boy to eat or drink anything that will make your rad level cross the 1001-Rad death threshold, a notice will say that you are affected by "fatal rad poisoning". At this instant you will not die; however exiting the Pip-Boy without taking any RadAway that would lower your radiation below 1001 will kill you instantly. If you do this it is interesting to note that fatal rad poisoning has an effect of -10000 HP so if there is a way to increase max HP in the console, then it could be possible to live with this stage of radiation without making yourself invincible. Another interesting thing to note about this stage of poisoning is that it will immediately drop your HP by 100, and each stimpak will decrease it by the amount they would normally heal you.
  • For short-ranged players it may actually be worth playing with 400 rads if you have the Rad Regeneration perk, and you don't mind the loss in Endurance and Agility. The regeneration of limbs is very fast, as any crippled limb will heal within a few seconds.
  • If you die in Fallout: New Vegas from drinking irradiated water, upon death the red diamond with exclamation point (same as the modded weathered 10mm pistol pre-patch) will appear.
  • Radiation in the Fallout games is both more and less lethal than it is in the real world. For example, common symptoms of radiation sickness (such as nausea and vomiting) will appear at around 1000 mSv or 1 Gy (100 Rads). 4000 mSv or 4 Gy (400 Rads) will lead to death in 50% of cases within a 4-6 weeks. 6000 mSv or 6 Gy (600 Rads) will lead to death in 95% of cases within 2-4 weeks. At 10000 mSv or 10 Gy (1000 Rads) a human will not die immediately as is depicted in the Fallout games but death occurs after no more than 2 weeks and it is a fatal dose in 100% of cases. A full body dose of radiation that could instantly kill a human would need to be in the tens of thousands of rads, even in a case involving a 30,000 rad exposure could still take as long as two days for death to occur. See Acute radiation syndrome on Wikipedia and the MIT Department of Nuclear Science & Engineering for more details on radiation poisoning in the real world.