What does the reading on a Geiger meter equate to in physical effects?

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I know 0.2 isn’t very worrisome but 1.5 is. What is the difference in the physical effects between these readings and readings 2.0+?

Thanks 🙂

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It’s usually sieverts if it is measuring dose, .2 would be worrying. 2+ would cause immediate radiation sickness. If it is mSv then neither is too troubling. If it isn’t measuring dose it is measuring instances of ionizing radiation in a set time period, minutes or seconds

It (of course) depends. In this case, it depends on the units that the counter displays.

Usually a Geiger counter measures something per unit of time. If you’re looking for contamination, that may be events per second. If you’re using it as a radiation exposure meter, it’s usually a unit like microGray per hour. Total dose is then calculated by integrating over the time you’ve been carrying the meter.

These alternative measurements are all based on the counts per second metric, where a “count” is an electron cascade initiated by ionizing radiation entering the Geiger tube. Usually this count per second measurement should be adjusted for dead time.

Usually Becquerels where i am which is basically number of radioactive particles entering the device per second.

“Geiger counters” usually measure in milli sieverts per hour. Which means that if you stood in that spot for an hour you would receive X miliseiverts of radiation.

It all depends on how long you are going to be exposed to that level of radiation. Radiation can hurt you one of two ways, either a massive amount will kill you quickly (think Chernobyl firemen) or a little every day will give you cancer (think skin cancer). As you probably saw in the TV show 3.6 isn’t great but not terrible either. You could work for a few hours in such conditions in an emergency. Unfortunately the real number was much much higher.

You can take a massive dose for a short period of time like the guys who cleaned off the roof at Chernobyl. They got the maximum “safe” dose in 90 seconds but they did not die from it. OTOH if you get an X-ray you will see the tech step out of the room when he shoots. One X-ray isn’t going to hurt you but he does a few hundred per day X 5 days a week X 20 years, that adds up fast. FYI a CT scan is a significant dose of radiation that you want to avoid if possible.

The real problem is radioactive dust that gets inside your body. That tiny speck of uranium gets down in your lungs and keeps blasting your lungs with radiation until it gives you cancer. Your body can deal with this to an extent, but there is a limit. This was the real problem at Chernobyl. Several tons of the radioactive fuel was blasted over the countryside.

Apropos of nothing, when I was in university, I worked a job driving radioactive waste generated by the labs around. We had a lot of fun playing with the counter and discovering latent radioactivity in lots of things, like bricks, eg.

[I have found this visualization of a radioactive material (uranium) helped me understand radiation more easily than many descriptions I read alone.](https://youtu.be/ZiscokCGOhs) The description of the video does a great job to explain the visualization in detail, I would recommend reading it fully. To crudely summarize what they have done is take a radioactive material and put it inside of a sealed box containing liquid alcohol and chilled to -40C. As a result ionizing particles and any traveling particles will leave a trail of condensing vapor behind them and allow these previously invisible radioactive particles to be seen by the naked eye. Note there are many different types of radioactive particles that have been observed to have different effects on cells and biology. Depending on what a Geiger meter is looking for (many can be set to measure different types of radioactive particles by using different filters over the sensor area) they are designed to make a noise when one of these particles hits a screen or sensor, and count these interactions over a period of time to give a reading of “radioactivity”. These particles can cause cellular damage to life when they collide directly with cells which isn’t likely but if you are exposed repeatedly or to a high dose of radiation, the odds of damage occurring increase.

P.S. if you watch closely you will occasionally see a trail from a particle that does not originate from the radioactive source. What you are seeing here is typically atmospheric or “background” radiation.

Also apologies for spelling in grammar and simplifications, editing to note I wrote this on my mobile so any corrections or additions are welcome!

It depends on what unit it is. The unit for dose is Sievert (Sv).

1 Sv is very serious and could kill you. 10 Sv is a death sentence.

Typical background dose is around 0.1 µSv/h or less. Which is like a hundreth millionth fraction of a lethal dose, *per hour*. So essentially harmless.

Likewise, 1.5 and 2.0 µSv/h are essentially harmless, but the increased dose rate could indicate the presence of some radioactive substance, which might warrant further investigation.

If exposed during a short time, you could crank it up to 1000s of µSv/h and there wouldn’t be any measurable effect on your body. However such high numbers would be worrisome if for example it was at your workplace or in your home, and you would be constantly exposed for months or years. Then you would be likely to eventually contract leukemia.

Also small note: a Geiger counter/meter measures activity. A dosimeter measures dose.

That little grainy clicking sound you hear are *subatomic particles slamming into a rod in the Geiger counter and producing a crackling like a spark or lightning bolt.*

The counter measures ionizing radiation. What makes something a radioactive material is that over time, it’s atoms break down and emit subatomic particles (like alpha or beta particles) as super high energy. These particles can “ionize” things they slam into — knocking an election free. The Geiger counter contains a high voltage spark gap and a gas that is easily ionized. When a particle slams into the gas and knocks an electron free, that free electron and the resulting ion (an atom missing an electron) slam into other gas particles and set of a chain reaction of ionization carrying current across that spark gap — something like a lightning bolt cracking through the atmosphere.

This same ionizing process (knocking free an electron) can happen in your skin or deeper organs when exposed to ionizing radiation. Like the gas in the Geiger counter, DNA is also easily ionized. If enough electrons get knocked out of your DNA, it can deform, mutate, or destroy the DNA. The body has ways of correcting this kind of damage (it’s somewhat similar to a sunburn).

But if there is enough of it, your body cannot fix the damage and you essentially end up without the ability to make new proteins of fix your cells. This is called severe acute radiation poisoning.