I recently learned about Cherenkov Radiation which produces an eerie blue glow, such as when viewing a nuclear reactor submerged in water. This effect was known about as early as the 1930's. However, nearly every representation of radioactivity and radioactive materials I've seen in popular media is associated with a bright green glow. Aside from radium being used in radioluminescent paint and uranium being used as a glass colorant, I have found few if any examples of this "green glow" in real life.

What was the origin of the association between radioactivity and the color green in today's media?

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    Hi, welcome to SF&F. Green glowing stuff being toxic/dangerous is common enough to be a trope: Sickly Green Glow (warning TVTropes).
    – DavidW
    Apr 2, 2020 at 21:58
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    As for the beginnings of a possible answer, I believe that radium - one of the first radioactive materials that people might have seen - has a greenish glow.
    – DavidW
    Apr 2, 2020 at 21:59
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    This article agrees with the theory that it's probably from radioluminescent paint which contained radium & phosphors. The phosphors give the green glow, pure radium itself has a slight bluish glow, due to its alpha radiation ionizing nitrogen in the air.
    – PM 2Ring
    Apr 2, 2020 at 22:07
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    @PM2Ring Ah yes, that was it precisely. The glowing watches. I forgot it was radium+phosphor.
    – DavidW
    Apr 2, 2020 at 22:38
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    The phosphor used in radium paint is sphalerite, aka zinc sulfide -- it glows a yellow-green color when excited by any sort of radiation. UV, alpha, beta, or it will even store energy from regular visible light and continue to glow for some time (minutes to hours). This is also what's found in most "glow in the dark" plastics and paints.
    – Zeiss Ikon
    Apr 3, 2020 at 12:10

2 Answers 2


This Quora question cites three possible sources:

The rumor is that reporters seeing the first nuclear reactors at criticality did so through lead-doped glass; when you dope glass with lead, it gives it a green tint - so the reporters, not having this explained to them, thought that radiation was green.


These are uranium ores, which are jade green crystals:
Image of uranium ores, which are jade green crytals

These are uranium glasses, which emit bright green light under UV illumination:
Image of uranium glass emitting a bright green light under UV illumination

Lastly, as mentioned in the comment above, the radioactive material people were most likely to encounter in daily life was radium, famously used in self-illuminating paint, which glows with a green light when combined with phosphorescent copper-doped zinc sulfide.

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    I think for completeness it would help to also mention the radium-doped phosphorescent paint as discussed in the comment linked above.
    – DavidW
    Apr 2, 2020 at 22:47
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    In the case of the radium paint, it's the paint that glows green rather than the radium itself. The invisible radiation from the radium excites a material in the paint. That stuff glows.
    – JRE
    Apr 3, 2020 at 5:45
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    @DonyorM: Maybe the same reason the Romans made drinking cups from lead, because they enjoyed some of the side effects.
    – FuzzyBoots
    Apr 3, 2020 at 12:55
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    @DonyorM, Why not? People were using uranium to color glassware and ceramic glazes since long before anybody knew that the stuff was dangerous. Apr 3, 2020 at 17:34
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    The trace amounts of uranium in ore don't give off a particularly harmful amount of radiation anyway; it's mostly "depleted" uranium, which is why it needs to be processed into fuel or (especially) weapons. It's more dangerous for its toxicity, similar to lead.
    – Cadence
    Apr 3, 2020 at 19:20

Clearly Radium Dials which were in relatively wide circulation before people decided to die in car crashes instead (image from wikimedia, user Arma95):

enter image description here

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    I'm a bit confused about your second comment about car crashes...
    – FuzzyBoots
    Apr 3, 2020 at 12:22
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    @FuzzyBoots It is a bit of a non-sequitur, I agree. I think he's referring to the idea that radium paint was used to make dials that glow in the dark (specifically, the dials on car dashboards,) but that practice was discontinued when other - non-radioactive - means of making them glow were discovered. So, people "chose to die in car crashes" rather than "to radiation poisoning from the dials." (I don't know how realistic that threat ever was, but I can certainly see it being a hot topic back in the day.)
    – Steve-O
    Apr 3, 2020 at 13:43
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    @Steve-O The dashboard dials, being behind glass, were pretty much harmless to the driver, unless you pulled it out and licked it. The only people that got radiation poisoning from those were the people whose job it was to paint them, and that was because they were wetting the brushes in their mouths. Alpha radiation (such as that found in radium paint) can do a lot of damage, but doesn't penetrate easily, so it's mostly only a problem if you directly ingest it. Apr 3, 2020 at 14:24
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    @Steve-O The health issues from radiation (especially the risk of ingesting or inhaling Radium traces after damaging a watch or clock) were being discovered around the time automobiles took off, which do a much higher damage to public health. Apr 3, 2020 at 14:47
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    @Peter-ReinstateMonica Don't worry, some of us got the joke.
    – barbecue
    Apr 4, 2020 at 16:10

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