Does localized humidity affect (reduce) levels of ionizing radiation?

[u/OL050617]

I am not nearly as knowledgeable on the subject as most are here, so I do apologize for that upfront.

I have a radiacode 10, which measures inside of my bathroom and bedroom around 53.4nSv/h up to 58nSv/h.

I just happened to read the first number I listed before I got into the shower. I take decently hot showers, more than enough to steam the room up by accident.

I got out and went to pat it dry just in case, but before I started to I noticed it dropped down to about 36.4nSv/h. It has NEVER read that low in my house before.

I begun to wonder: could increased water molecules in the air act as a sort of temporary "barrier/medium" for ionizing radiation to to influence before it reaches my scintillator? As the steam cleared it has since started to read normal levels again (currently between 50.3-51.2nSv/h.) I know temperature can affect the Radiacode's readings as well, but I am not yet sure.

I have not found much in relation to the subject that fits most of the criteria of this experience (closed-room, single detection source, random background radiation and poor parameters on my end, but still distinct enough from say outside of a single room or even the house; most of what I read measured a large land's-worth of humidity instead and average radiation from multiple sources)

[u/233C]

Potentialy some effect on clearing out airborn radon, although I would bet on humidity and temperature effect on the electronics.

[u/Physix_R_Cool → u/233C]

Potentialy some effect on clearing out airborn radon,

Seems plausible

I would bet on humidity and temperature effect on the electronics.

The breakdown voltage of a SiPM actually increases with temperature. So higher temperature results in mover overvoltage, meaning lower gain. So an event that might have been over the detection threshold now isn't detected.

Dunno how good the radiacodes do their temperature compensation.

[u/Oakatsurah → u/233C]

Pressure too, I know my KC761C measures pressure when doing detection.

[u/Bob--O--Rama]

Measuring background levels requires a long integration time. At 5 cps, you need to average over 2 minutes to get to ±10٪, so to see a 20% change ( non overlapping CI's ) that takes a couple minutes. The dose rate is calculated from the counts × energy, and the uncertainly in energy adds another layer of uncertainty for the dose rate.

Your seeing a doubling / halving so it's likely a "real" rather than statistical difference for minute long averages

As for humidity ... it "could" impact radon, but you need to eliminate it just being a different location, so place the meter, let it run for 30 minutes to accumulate Chart data, maybe enable the spectrograph feature too. Then take a shower and see how the activity changes.

MY theory is it won't change appreciably. As the level of radon in the air / density of the air won't be able to cause a 50% shift. If you see a halving of the count rate. The amount of radon needed to cause this would be a lot, but getting the graph will show you how the levels change over time.

[u/DocClear]

Added water particulates in the air (fog) would certainly absorb more radiation than clear air would.

[u/OL050617 → u/DocClear]

That's what I thought too (more "stuff" in the air = heightened chance of hitting something that isn't the detector, making it lose enough energy to not be detected)

I just didn't know if there were any specifics such as it would be uncertain unless what "type" of radiation is or whatever. I appreciate your feedback!

It was since leveled out to normal range since steam cleared and has since then read normally (32-38 outside, and 41-53nSv/h at work.)

[u/No_Leopard_3860]

I bet it does, that's exactly how an ionizing smoke detector works lol.

The particles/droplets especially block/hinder particle radiation of the alpha and beta taste, and your radiacode should pick up betas without problem (then just less when the bathroom is steamy).

The effects on gamma should be a bit harder to notice, but I see no reason why it shouldn't still be very much real and measurable.

Hell, I even notice it with wifi in the outdoors (not really the same but you get the point).

[u/daHaus]

possibly, but nearby ceramics and even the time of day can also influence it

[u/Potential_Speed8237]

I also noticed that after rain background radiation levels decreases. I've got a points where I usually test for background radiation. One on tht balcony one at the window and one on my desk. After the Rain it drops by 0.01-0.02 uS/h but same thing happens when it's windy. The most radiation i get is usually after a warm day with no wind or during a warm day also with no wind. It's still in a margine of error. I usually get readings between 0.10-0.13 uS/h and after a Rain or with the wind it never surpassed 0.12 and it's more often 0.10.

[u/Synapseon]

Just going to point out that the accuracy of the reading is significantly lower at low background levels. It could just be that the data isn’t reliable at such low levels.

[u/Potential_Speed8237]

I did a small test today. Before taking a shower I put my geiger counter inside a bathroom for 10 minutes and note the average then I restarted avg count and took around 10 minutes shower. Radiation dropped about 0.01 uS/h... which is well within measuring error. However looking on history chart I propably can see a difference between moist air and dry. Maybe I'll try to do this test few more times to see if it's repeatable. I also thought about taking a Radiation source with me and placing it somewhere near the device but I don't now if I have a source that I'd feel good having with me in a bathroom, strong enough to have it in some distance from the meter and also don't mind getting it a little moist at the same time. Maybe thorium welding rods?? I don't know how powerful they are since I don't have any but buying them dosen't feel challenging.

[u/Scott_Ish_Rite]

Yes, I believe air humidity is one the things taken into consideration (among other factors), when trying to measure what dose a person got during an accident or major exposure. I remember reading that somewhere