*Chair* from Half-Life (2017) by Elliot Walker. Hot sculpted uranium glass. Pictured above at Two Temple Place, London in the exhibition 'The Glass Heart: Art, Industry & Collaboration', 2024.

‘Radiation risk is not an easy matter for most people to grasp: we cannot see, hear, feel, or smell radiation.’ [1]

What follows is my attempt to make sense of my rather basic measurements of the ionising radiation emitted by Elliot Walker’s glass chair in the simplest way possible – a complicated task as there are a number of variables which need to be considered.

I’ve always been intrigued by radioactivity, but it was when I learned about the 2011 nuclear accident in Fukushima, Japan, that I began research the subject in depth. Not only was I was fascinated by the complex science, but I was also intrigued by how other artists responded to radioactivity in their work. [2]

*Deserted high street, Chuo district, Tomioka, Fukushima, 9km south of Fukushima Daiichi nuclear power plant,* Lis Fields, 2016 [3]

So I was excited to discover Eliot Walker’s uranium glass chair, on exhibit at Two Temple Place. Beautiful and sinister, with an ethereal glow, it was as if an antique Windsor chair had been transformed from wood into glass by alchemy, or by magic like in a fairy tale.

It’s proportions were unusual for this style of chair, like those of a child’s high chair – in which case the work of an evil scientist or malevolent fairy? – or those of a glass chair which was beginning to melt, and if I waited long enough I might see it lose its shape altogether and flow onto the gallery floor.

The actual timespan of the flow of solid glass, at room temperature, en route to settling into stable crystal, is mind-boggling – at many more billions of years than the age of our universe i.e. at least 14 billion years.

As for the uranium, which gives the chair its translucent chartreuse colour, the timespan of its transformation into non-radioactive lead is a bit shorter: 4.5 billion years for half of it to turn into thorium-234, the first of 17 shorter half-lives before it becomes stable lead as you can see in the diagram below:

I’d seen a fair bit of uranium glass but this chair was by far the biggest piece I’d ever seen – by a long shot.

Just as I expected, its luminous chartreuse colour turned a bright fluorescent green in the beam of the gallery attendant’s UV torch, as do my antique amber uranium glass beads (below).

I also have a Mid-Century grapefruit dish (below) which gives off a lot of low-level radioactivity at a close range i.e. within a couple of centimetres.

As the dish and beads are tiny compared to the chair I was curious to know just how radioactive the chair might be, so I returned to Two Temple Place with my Geiger counter (radiation detector) to take some radiation measurements aka readings.

Uranium oxide is believed to have been used to colour glass since at least Roman times. [4] But it wasn’t until it was identified as an element in 1789 that it began to be widely used in the production of domestic glassware.

After WWII the uranium oxide used to colour glass was typically derived from depleted uranium – a byproduct of the nuclear power and nuclear weapons industry. [5]

The dose limit for civilians in most of the world [6],[7] of ionising radiation, from all sources, including nuclear power plants, is 1mSv/a (1 millisievert per year) [8].

I’ll therefore use 1mSv/a as a reference dose when discussing the radioactivity of Eliot Walker’s uranium glass chair.

As almost all scientists believe that there is no dose of ionising radiation which doesn’t carry some degree of risk to your health, it might be wise to avoid knowingly subjecting yourself to unnecessary additional doses by sitting on the chair for 3.5 hours every day for a year, tempting as that may be. And you don’t have to move very far from the chair to avoid it’s radiation altogether.

If, however, the chair were to be smashed and you breathed in or swallowed the glass particles your risk of harm would be greatly increased. This is because the short-range radiation emitted by Uranium glass is far more dangerous when inside your body than than from the outside.

Victorian uranium glass beads with tiny, nearly microscopic chips

As you can see in the photo above my Victorian uranium glass beads have many tiny chips along their edges. In addition to the external dose of low-level gamma, beta and X-ray radiation I’d receive were I to wear them against my skin for any length of time, I’d be concerned about getting any radioactive dust or chips inside my body, where they could become stuck to my cells and continuously bombard them with radiation, for some time after I’d taken the necklace off.

The risk of harm as the result of internal exposure to ionising radiation is why, for example, so much effort is put into reducing radon gas in homes, because it can attach to particles in the air which can be inhaled and become permanently lodged inside the lungs.

The harm to your health as the result of exposure to ionising radiation – from any source – is cumulative, which is why there is a limit to the number of years airplane crew and other radiation workers can work in their professions [9].

The risk of harm is greater if you are female than if you are male, greater still if you are a child or an elderly person, and greatest of all if you are a foetus in utero – which is why medical professionals avoid giving pregnant women X-rays.

When making sense of measurements of ionising radiation, context is essential.

Hence I’ve made a graph in which I compare the results of a number of five-minute readings of the three radioactive objects, at various distances and with various levels of shielding, plus readings of the background levels in the rooms containing the objects:

When I held my Geiger counter 1cm away from the chair for 5 minutes it detected a total of 887 radioactive counts – aka decays – the count of the number of times radioactive atoms in the chair decay and gave off energy in the form of ionising radiation.

After converting 887 into millisieverts, the unit in which dose is measured, I calculated that, according to my measurements, you would need to sit on, or lean against, the chair, nonstop, for nearly two months or 54 days or 1,290 hours – or sit on/lean against it for 3.5 hours every day for a whole year to receive an equivalent dose of 1mSv per year.

However my measurements are pretty crude: 5 minutes is a short time in which to ascertain the average level of radioactivity of an object or an environment, e.g. 24 hours would give far greater accuracy. And it would be even better to measure all the objects – chair, necklace and grapefruit dish – in the same place, ideally in the controlled environment of a lab, and to mount the detector on a tripod to keep it perfectly still.

For the greatest accuracy of all I’d need permission to chip off a small sample of glass from the chair in order to do a more complex radiological analysis with a range of sophisticated laboratory equipment.

Like all other radioactive materials uranium contains unstable atoms which decay and release energy in the form of ionising radiation. The ionising radiation released by uranium is mostly alpha particles with some beta particles and relatively weak gamma rays and X-rays.

My Geiger counter can detect these four kinds of ionising radiation:

a = alpha radiation aka alpha particles

b = beta radiation – strong only

g = gamma radiation

X-rays

So, when I pop it in a plastic bag all alpha radiation is blocked and it only measures the strong beta, gamma, and X-ray radiation. When I cover it with ten sheets of aluminium foil, the beta radiation is blocked as well, so only gamma and X-rays are detected.

The significant quantity of weak gamma and X-rays I detected from the chair, necklace and dish, most likely come from the bismuth-214 [10] and lead-214 [11], into which some of the uranium has decayed.

ESTABLISHING THE BACKGROUND RADIATION LEVEL IN THE ROOM CONTAINING THE CHAIR

Distance from chair: 4m

Total radioactive decays detected: 228 (total counts)

= 45.6cpm (counts per minute)

= 2.27 mSv per year (millisieverts per year)

2.27 is slightly below the UK average background level of ionising which gives a dose of 2.70mSV/year [12].

In parts of Cornwall the background dose level can be as high as 7.80mSv per year. This is understood to be due to the abundance of granite rock there which emits ionising radiation directly and also radon gas which itself emits ionising radiation when it decays.

Stone, concrete, brick and ceramic tiles all contain varying levels of radioactive materials, such as uranium, radium and thorium, which emit ionising radiation as they decay. I live in a concrete building and the background radiation in my study gives me a dose of around 1.29 mSV/year.

Had the radiation I detected in Two Temple Place and in my study come entirely from materials originating in a nuclear power plant it would be over the dose limit of 1mSv/year for most citizens in the world, a dose which is in addition to “background” radiation, e.g. radon from rocks, rain water, snow, cosmic rays, plus medical radiation i.e. X-ray exams and radiotherapy.

When calculating the risk posed by a dose of ionising radiation, context is essential.

While the chart below is a good visual aid for comparing approximate doses quantitatively it does not compare them qualitatively: it doesn’t, for example, distinguish between external doses (outside the body) and internal doses (inside the body); it doesn’t tell you what type of radiation has generated the dose, i.e. alpha, beta, gamma, or X-ray and it doesn’t tell you the size of the area of your body receiving the dose.

The risk from the dose you will get from eating one banana, for example, is not equivalent to the risk from the dose you could get from living within 50 miles of a nuclear power plant [13] for a year, because the radioactive potassium-40 in a banana is quickly eliminated, while the radioactive materials from a nuclear power plant tend to be retained in your body for longer.

*Cesium-137 vs potassium-40: some radionuclides are more harmful inside your body than others,* Lis Fields, 2016 [14]

The risk from the dose of highly focused X-rays targeted at your jaw during a dental exam is not equivalent to the risk from the same dose of cosmic rays passing through your whole body during an airplane flight because the latter dose is to your whole body, in which different organs have different levels of sensitivity to ionising radiation.

Lis Fields is an American-born, UK-raised artist based in London. Her academic background is in science and art history, and she has subsequently worked as a scientific researcher as well as in film, and as an artist and designer in New York, Los Angeles and London. Her work reflects interests in medicine and health, psychoanalysis, education, the environment and human rights. The 2011 nuclear disaster in Fukushima, Japan, led her to take a particular interest in issues around radioactivity. In 2016, she participated in a study tour of Fukushima, examining the effects of the disaster, and she brings her expertise to bear unusually in the article above, considering an artwork, Chair from Half Life by Elliot Walker, recently featured in the exhibition 'The Glass Heart: Art, Industry & Collaboration' at Two Temple Place, London. You can see Fields’s two projects about the Fukushima nuclear disaster here: www.lisfields.org and here: www.redkimono.org

FOOTNOTES:

Dr Ian Fairlie and Cindy Folkers. The Scientists Who Alerted us to the Dangers of Radiation, 2024: https://ethicspress.com/products/the-scientists-who-alerted-us-to-the-dangers-of-radiation?_pos=1&_sid=000389670&_ss=r
e.g. Trevor Paglin’s Trinity Cube, also made from radioactive glass – from Fukushima and the New Mexican desert in which sand was turned to radioactive glass during the Trinity test of the first nuclear bomb: https://paglen.studio/2020/01/21/trinity-cube/
Photo from 20 millisieverts per year, an exhibition about the 2011 Fukushima Daiichi nuclear disaster: www.lisfields.org
Dr David Hobart, Los Alamos National Laboratory, the US lab at which J Robert Oppenheimer led the team who developed the first nuclear bombs: https://periodic.lanl.gov/92.shtml
https://spark.iop.org/uranium-glass
i.e. the equivalent dose i.e. the average dose received by the whole body: https://www.cnsc-ccsn.gc.ca/eng/resources/radiation/radiation-doses/
Except for people in Fukushima, Japan, since the 2011 nuclear accident, as I explain here: https://lisfields.org/20msvyear/
http://web.archive.org/web/20190403031313/https://nucleonica.com/wiki/index.php?title=Radiological_limits
http://web.archive.org/web/20190403031313/https://nucleonica.com/wiki/index.php?title=Radiological_limits
Uranium, US Geological Survey: https://pubs.usgs.gov/of/2004/1050/uranium.htm
George Chabot, 2016, Health Physics Society: https://hps.org/publicinformation/ate/q7546.html
UK dose figures cited by Steve Fisher of the UK NDA (Nuclear Decommissioning Authority) in his 2015 presentation: http://web.archive.org/web/20160302230314/http://nuclearrc.sa.gov.au/videos/effects-and-threats-of-radiation-151215-630pm/
Moreover, providing a single dose figure for people living within 50km of a nuclear power plant – even if it is correct – is highly misleading, even if it is an average, because those living 1 mile away, for example, will receive a far higher dose than those living 40 miles away.
Photo from 20 millisieverts per year, an exhibition about the 2011 Fukushima Daiichi nuclear disaster: www.lisfields.org

HOW RADIOACTIVE IS THE GREEN GLASS CHAIR?

ESTABLISHING THE BACKGROUND RADIATION LEVEL IN THE ROOM CONTAINING THE CHAIR