Answer to Question #13786 Submitted to "Ask the Experts"

I have been researching civil defense procedures, advice published during the Cold War, and the potential threat of nuclear war and its aftermath. There is one question for which I cannot find any current information. In the event of nuclear war, either limited or total, what would be the maximum level of daily exposure that a human being could endure without acquiring Acute Radiation Syndrome (ARS). I recall reading somewhere that a person could remain symptom free if his exposure did not exceed six roentgen (R) per day. That sounds like a lot to me. Is there any more current information on this subject. Thank you!

So, there are a few issues here:

1. How much radiation does it take to get radiation sickness?
2. What's current guidance on radiation exposure after a nuclear attack?
3. Is 6 R (equivalent to roughly 60 milliGray [mGy]) per day a big deal?

Let's tackle these one at a time.

1. It takes about 1 Gy of radiation to the whole body to start to make someone sick, and at this dose it might take several weeks to start feeling ill from ARS. If you're exposed to 1 Gy all at once, you’ll likely start to feel a little ill in a few hours and that will pass within a half day. Then you'd feel fine for a few months until the ARS kicks in—nausea, vomiting, weakness, etc. If you receive the 1 Gy over an extended period of time, then it will take a higher dose to cause the same symptoms because your body will be repairing the damage—think of a bathtub that you dump a truckload of water into all at once versus one with the drain open, removing some of the water as it's coming out of the faucet. In the event of a nuclear attack, if you're sheltered so that you're accumulating radiation dose gradually then the effects will be less than if you're standing outside basking in the fallout as it drifts down from above.
2. The current guidance on dose after a nuclear attack is largely to do your best to minimize it as much as possible. Go indoors immediately—preferably towards the center of a large building, and at least a few floors down from the roof. Stay there until you are told it's safe to evacuate or to go outside. If you are outside in the centerline of the fallout plume you will likely die—if you are inside, then you will almost certainly live. You don't need to shelter for weeks—only for a few days, until radiation levels drop to where you can survive evacuation. That being said, you don't need to go all survivalist, stocking up hundreds of gallons of bottled water and energy bars—you won't starve or die of thirst in the time you'll need to shelter. (As an aside, if you have a child at school, you have to trust the school to be protecting your child. If you are in the fallout plume and you leave your shelter to bring your child home, you will likely both die from radiation exposure. You have to trust the teachers to take the right actions—there is nothing that you can do that will be helpful.)
3. Sixty 60 mGy per day is not going to kill you in the short term and, over the long term will increase your risk of cancer by a few percent (depending on the total dose you receive). If you receive 1 Gy in total—about 16 days at 60 mGy daily—then your lifetime cancer risk will increase by about 5% over the next few decades. That's not nothing—but it's also a 95% chance that nothing will happen.

For newer information, Lawrence Livermore National Laboratory has published several documents that are interesting reading. Here's a sampling:

• National Capital Region: Key Response Planning Factors for the Aftermath of Nuclear Terrorism
• Preparing for the Aftermath of a Nuclear Detonation; An Analytic Framework for Disaster Management
• Healthcare Challenges After Radiological Incidents Q&A
• PrepTalks: Saving Lives After a Nuclear Detonation [video]
• Key Response Planning Factors for the Aftermath of Nuclear Terrorism

P. Andrew Karam, PhD, CHP