AI-generated image
WHEN you think of radioactive material, one would immediately associate it with a green glow.
Take the opening sequence of The Simpsons animated series, for example, where the Homer Simpson, who works in a nuclear power plant, handles a green radioactive substance.
This green glow has been a powerful visual trope for a long time. However, is it true that radioactive materials glow green?
Verdict:
FALSE
When radioactive materials emit radiation, not only does it not glow green, it does not glow at all.
Ionising radiation, while technically a form of light, exists at high energy levels invisible to the human eye.
The most likely reason this myth came about is due to radium being used in the early 20th century to make luminous paint.
When mixed with a phosphorescent (a material that can absorb energy) such as copper-doped zinc sulfide, the radioactive properties of radium will cause the material to glow.
This is because as radium decays, it releases a lot of alpha particles (the helium nucleus of its atoms) and these particles excite electrons in the phosphorescent making it glow a bright, dare I say, radioactive green.
This process is called radioluminescence.
Its ability to make things glow radium was very popular back in the day and the paint was used in almost everything from night-time navigation instruments and glassware to even toothpaste.
One of the more tragic stories to come about during the era of radium's popularity was that of the "Radium Girls".
The US Radium Corporation produced green-glowing paints, sold under the name "Undark", used to paint the numbers on watch dials.
The workers, all women, had to use very fine brushes to paint the numbers on the watch faces and they were instructed to "point" their brushes by pressing them against their lips.
This meant that they unfortunately ingested small amounts of radium with each brush stroke.
These women suffered horrible diseases from the radiation and died horrible deaths, and some of their graves are radioactive, even up to this day!
However, the radium which killed them did not have a green glow - it was the phosphor that glowed green.
Fortunately, in modern consumer products like watches and glow-in-the-dark stars, the radioluminescence has been replaced by photoluminescence aka phosphor that emits light of one frequency after absorbing photons of a different frequency.
These glow-in-the-dark items recharge to full brightness after brief exposure to sunlight or a fluorescent light only to dim again over a couple of hours are photoluminescent and contain no radiation. Hence, it is much safer.
Just keep in mind, radioactive materials in pop culture glow green comes from the notion that the colour is also associated with poison and danger.
References:
1. https://www.mentalfloss.com/
2. https://rinconeducativo.org/
3. https://www.abc.net.au/
