Remember the model of an atom from your high school science class? Then you might also remember the core principle that when the nucleus of certain materials breaks down, it releases energy in the form of radiation.
Source: EPA
Radioactive material doesn’t just linger—it clings. It can stick to clothing, skin, hair, food, and even the ground. Wind can carry radioactive dust for hundreds of miles, contaminating buildings, water, and crops in its path.
The worst part? You can’t see it, smell it, or taste it. Some fall gravely ill within days, while others suffer silently for years, never knowing the cause.
In this guide, we’ll break down the health effects of radiation exposure, how to protect yourself, and how to recognize the danger before it’s too late.
Ionizing Radiation How is Radiation Measured? The Radiation Hazard Scale Sources of Radiation Radiation Protection Health Effects of Radiation What is a Lethal Radiation Dose? What Can You Do After Exposure to Radiation? Conclusion: Avoid, Protect, Remediate FAQTable of Contents
Ionizing Radiation
Natural radiation comes from many sources, including minerals, space, uranium in the ground, and some even comes from the human body.
This is generally called "background radiation" and varies slightly depending upon where you live.
"Ionizing radiation," on the other hand, presents a drastic threat to human cells. Ionizing radiation comes from destabilized atoms that emit energy as they try to become stable. This energy can enter human cells and destabilize those atoms, wreaking havoc on the body's systems.
Source: Wikimedia Commons
How is Radiation Measured?
There are several ways to calculate radiation. Radioactivity is measured in units called Curie (ci) and becquerel (bq). These units are mostly used by scientists, so we'll focus on the units measuring the amount absorbed by the human body.
This is the milliSievert, also called the "effective dose."
This is a standardized measurement that tracks how radiation is absorbed over your entire body.
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A "Normal" Dose of Radiation
The average person in the United States has an annual radiation dose of 6.2 milliSieverts.
This comes from a variety of sources, including x-rays for medical causes, space, naturally occurring radioactive sources like radon, and the like.
People living in higher elevations, like Denver, Colorado, receive slightly higher doses of radiation simply by living closer to cosmic radiation.
Radiation from Medical Imaging
Many people worry about radiation from x-rays, CT scans, MRIs, or mammograms.
These tests are closely tracked to make sure that patients aren't receiving excessive amounts of radiation. A single chest X-ray, for example, exposes you to 0.1 millisievert, or about the same amount of radiation you receive over 10 days.
The Radiation Hazard Scale
The Center for Disease Control and Prevention (CDC) has released a color coded chart to quickly communicate threat levels in case of a radiation emergency.
Source: CDC
For those who don’t know, these are not hard and fast lines. The amount of radiation that it takes for the government to declare a shift from level 1 to level 2 depends on the typical amount of background radiation in a region.
Sources of Radiation
Certain types of radiation are worse than others. Non-ionizing radiation includes microwaves, baby monitors, and GPS systems. This kind of radiation doesn't penetrate the human body or cause damage.
Ionizing radiation is the source of health threats to humans, but low doses are tolerable with no negative health effects. Even living near a nuclear power plant is only estimated to give around 0.01 millisievert worth of radiation.
Source: EPA
What about a nuclear attack, however, or an industrial accident like Chernobyl?
This can release large amounts of radiation, affect a several-mile radius, and can continue to release radiation up to 48 hours after the initial blast.
Even well-designed, modern nuclear power plants can experience disaster. In 2011, the Fukushima Daiichi power plant in eastern Japan was struck by an unusually high tsunami. The cooling systems were disabled by the flooding and the radiation was released from the nuclear reactors. Over half a million local residents were evacuated.
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Radiation Protection
To protect yourself from direct exposure to radiation and fallout, you need to ensure you’re not ingesting or making any direct contact with radioactive materials. During a radioactivity emergency, that means full-body CBRN gear and a respirator with the appropriate filters.
Geiger-2 Dosimeter - Geiger Counter
In the event of a nuclear disaster, it often takes weeks or months - if ever - to determine how far radioactive material has spread.
If you’re ever concerned—or even just curious—you can activate the Geiger-2 and get a nearly instant reading of background radiation.
Using the simple two-button interface, you can track your accumulated exposure over weeks. You can also set customizable exposure limits—the unit’s integrated alarm will let you know when you’ve reached your programmed limit.
Thyrosafe Tablets - Potassium Iodide
The health risk can be minimized by reducing the amount of radiation absorbed by your thyroid. The isotope iodine-131 is a common byproduct of nuclear power plants, explosions, and meltdowns. When humans are exposed to I-131, it accumulates in the body’s thyroid gland and emits 90% of its energy as damaging beta radiation. Even limited exposure to I-131 can lead to thyroid cancer and death.
Using Thyrosafe tablets floods your system with stable potassium iodide, providing far more than the recommended daily allowance. As a result, your thyroid becomes functionally incapable of absorbing any more, so it can’t absorb damaging I-131.
It's important to note that this is not to be used as a preventative measure. As an intervention after radiation exposure, however, it can be life saving.
CM-8M Full Face Respirator
To avoid getting ARS, you mustn’t ingest any radioactive particulates or fallout. That’s where your CM-8M Gas Mask comes in.
Respirators are essential for ensuring an airtight seal around the sensitive soft tissues on your face, including eyes, nose, and mouth. Standard sized 40mm NATO filter cartridges purify the air you breathe, protecting you from exposure to ionizing radiation. This is crucial if you have to travel through or work in a radiation-exposed environment. In fact, workers exposed to occupational radiation are required to wear protective equipment like a respirator in many cases.
There’s a speech diaphragm for communicating while wearing your mask. You can mount your filter on either side depending on whether you’re left- or right-handed, and it’s compatible with accessories like the MIRA Safety Gas Mask Microphone or a drinking system.
Its 20-year shelf life keeps you prepared for any sudden emergency.
CBRN Hazmat Suit
Radioactive materials cling to clothing and shoes. It permeates the skin, allowing it to get inside the skin and disrupt vital organs.
Since it’s crucial to avoid direct contact with radioactive fallout, you’ll want to ensure that you’re wearing a complete protective kit—starting with a hazmat suit like the MIRA Safety HAZ-SUIT. It’s designed to be reusable and is available in various sizes for each member of your family. Entirely impermeable to CBRN threats with a practically unlimited shelf life, this is an excellent option for every member of your party.
Health Effects of Radiation
Large doses of radiation taken in over a very brief period of time cause acute radiation syndrome (ARS). This was found in the survivors of the Hiroshima and Nagasaki bomb attacks and first responders of the Chernobyl nuclear disaster.
Acute Radiation Syndrome
This is the type of "radiation sickness" usually depicted in film. Large doses of radiation (1 sievert and above) can start the process of ARS in various locations across the body. Common systems include the gastroenterological (GI) tract, the circulatory system, and the bone marrow.
The timeline for ARS can vary. A common symptom during this initial phase is nausea and vomiting. The higher the radiation dose, the sooner an individual is likely to begin vomiting. If vomiting starts within an hour of initial exposure, long-term survival is unlikely. With bone marrow ARS, the symptoms begin within 1–2 days.
At higher radiation doses, other symptoms may appear in the first few hours—including diarrhea, headaches, fatigue, weakness, hypotension, fever, and nausea. The face may begin to take on a reddish color. At extremely high doses, radiation can cause an individual to lose consciousness within hours.
With GI ARS, initial symptoms typically start within hours, whereas those with cardiovascular ARS start experiencing symptoms within minutes.
Regardless of when the symptoms start, many cases are so severe that the individual is effectively immobilized. Thus, if you’re knowingly exposed to radiation, you should seek shelter and safety as soon as possible.
Incubation/Latent Phase
Radiation sickness has a strange trajectory. Though symptoms can appear mere minutes after large-dose exposure, they can go away again for several weeks.
With proper medical attention, some people can survive the initial phase of ARS (called the prodromal stage). The cellular damage is often too much for the body to recover from, however.
Survival Outlook
Recovery from ARS depends on what kind of ARS is developed:
- GI tract
- Bone marrow
- Cardiovascular/central nervous system (CNS)
Some individuals will show symptoms of GI ARS at just 60% of what’s considered to be a minimal dose. These individuals might seem more susceptible to radiation sickness, but they’re far more likely to survive.
Most individuals suffering from bone marrow ARS will recover within a few weeks to two years. Bone marrow cells gradually begin to repopulate, elevating blood cell counts and restoring the immune system’s ability to ward off infections. During this time, patients must stay under observation by their physician in a safe environment.
Other forms of ARS are generally fatal. Those with radiation doses as low as 6 Sv can still be fatal. For those who survive, lifelong consequences include elevated cancer risk, infertility, persistent health problems, and more. Symptoms can manifest months or decades later—seemingly unconnected to the initial radiation exposure.
Cancer
The average American has a 22% chance of developing cancer sometime in their life. Radiation increases this risk exponentially.
It's currently unknown exactly how much more likely you are to develop cancer at low levels of exposure to radiation - meaning under 100 millisieverts. Public health officials operate with the "“as low as reasonably achievable” yardstick. This means that we assume all radiation carries some risk of cancer.
As the radiation damages cells, the body rushes to repair them. Sometimes the process is flawed, causing mutations and eventually tumors.
Source: EPA
What is a Lethal Radiation Dose?
Surprisingly, not everyone reacts the same way to radiation. For some reason, some people are better able to withstand cellular damage.
A lethal dose is considered one that will cause death to 50% of people within 30 days (the 50/30 rule).
The U.S. Nuclear Regulatory Commission puts this number at 4 or 5 sieverts in a short period of time (hours or days).
Remember, the average person has an annual dose of 6.2 millisieverts of exposure. A millisievert is 1/1,000 of a sievert, so 4 sieverts is far, far more than you will ever be exposed to accidentally - without a nuclear threat or accident taking place.
What Can You Do After Exposure to Radiation?
The best way to avoid radiation sickness is to avoid large doses of radiation at all costs.
If you do find yourself exposed, decontamination is absolutely essential.
Contrary to popular belief, radiation isn't contagious. If someone has been exposed to radiation in the past, that doesn't mean that they currently pose any danger to other people. They may live with the health effects permanently, though.
That said, non-decontaminated material can remain dangerous for decades. An infamous example is the firemen of Pripyat. They did not wear proper protective clothing during the 1986 Chernobyl nuclear power plant malfunction and their clothes were badly contaminated. The clothes were taken to the basement of the Pripyat Hospital and remain there to this day - still highly radioactive.
The current hospital workers aren't under threat from the clothing - it would need to be handled directly to be dangerous.
READ NOW: Radioactive Survival Lessons from the Chernobyl Nuclear Disaster
Conclusion: Avoid, Protect, Remediate
High levels of radiation exposure cause symptoms within hours. Exposure in excess of 700 millisieverts can often cause nausea, vomiting, and cellular damage. It can also increase your risk of cancer, with children and infants being especially vulnerable.
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The best solution, as with any CBRN threat, is simple: Avoid radiation at all costs. Immediately evacuate an area with extremely high concentrations of radiation, and don’t stay too long in an area associated with a cancer cluster, toxic waste, or other potential radioactive threats. Stockpile key gear, like P3 Reactor filters, gas masks, and hazmat suits.