[Andy Saunders]

This has been sent to me by a major player in the historic warbird field in light of recent events. I post it without further comment (and with his permission) save to say that it may provoke some more useful and informed debate on this forum:

Ex-military Instruments with Radium (luminous) Dials.

Below is a short dissertation on the subject, written not by a specialist, but an aircraft restorer with an enquiring mind and is based on published data easily accessible.

Dealing with any instrument containing Radium 226, is fraught with dangers and it must be clearly understood there is no known safe limit of the radiation emitted. The Dutch collector who had his many instrument panels confiscated may have had his life saved. Read on and see why.

The luminous paint is made up of three main constituents, including the subject material Radium, which reacts with another compound in the paint creating the luminous effect; there is also a binder in the material to hold it together in the form of paint. It decays to a light/dark brown colour over age and is usually quite easy to spot in an instrument.

This element, Radium (Ra) with the atomic number 88, is 1,000 times more radioactive than Uranium; it is one of the most radioactive elements known to mankind. The isotope Ra-226 has a half-life of some 1600 years and decays into Radon gas.

Radium emits Alpha, Beta and Gamma rays. The glass will stop the Alpha particles (very dangerous), and most of the Beta, but the Gamma(also potentially dangerous)can only be stopped with a thick layer of lead. Radon gas will also be present but will dissipate in a ventilated environment. The radiation damages living cells and is absorbed into the bones, as there is a similarity to calcium but the body cannot differentiate between the two elements in the processing of ingested material. The greatest danger is the dust that is released when the instrument is disturbed; breathe it in and you will be building up serious trouble for your health. The dust will contain Alpha particles which, once free can do the greatest damage if absorbed by the body. I quote from Wikipedia on the subject: ”Because of the high mass and strong absorption, if Alpha emitting radio-nuclides do enter the body (if the radioactive material has been inhaled or ingested), they are the most destructive form of ionizing radiation….and large enough doses can cause any of the symptoms of radiation poisoning…. etc”. Well worth a read if you are in any doubt of what you are dealing with.

As can be seen, the greatest danger is the ingestion of the dust from a broken instrument, or by the casual removal of the luminous paint. As far as is known there is no facility for removing this material and in anycase it will have irradiated the material around it. Under NO CIRCUMSTANCES should these instruments be kept in your home – especially a bedroom, and concentrations of individual instruments should never be greater than 25-30.

We have all dismantled these instruments at some stage and while it is not known how little contamination is ‘safe’, it should be assumed that ‘nothing at all’ should be the base line. Obviously, the closer you are to the source, the greater the danger and of course the duration of exposure is relevant.

So – what next? There is a remote danger of terrorists buying up quantities of these instruments, removing the radium in dust form - ensuring by doing so their imminent passage to the thereafter - mixing with a drying clay or similar and packing around a conventional explosive device. They won’t be bothered with making a nuclear bomb from these minute quantities of radioactive material, but making a so-called ‘dirty bomb’ scattering this dust and causing mayhem in the process, as the cleaning up will be a very long and expensive process. We must all therefore be aware of this and be careful who buys the instruments if you sell them. There is certainly a duty of care if nothing else, as if – God forbid – a dirty bomb was set off in a sensitive public area, then our hobby of old aviation may be over in a flash (not a nuclear one but a legislative one!).






That’s the bad news, but is there any good? Are we allowed to possess these instruments? Under the Atomic Energy and Radioactive Substances Act (1985 no.1048) The Radioactive Substances (Luminous Articles) Exemption Order 1985, it seems possibly so, providing the maximum number of Becquerel (per instrument) does not exceed certain limits. There are other conditions and one is that the source is kept behind glass and there are also restrictions on disposal. Under UK law it seems that the collector in Holland may have been allowed to keep his panels, but from a practical point of view he was playing with fire. There are common sense rules, not just the law of the land that you need to take heed of. You also need to be aware that some of the earliest instruments from the 1st World War for example – have the greatest concentrations of this compound.

Be aware – there are many radiation meters available on e-bay, but the vast majority are surplus items that are either broken or inaccurate, or mainly designed to detect the results of an atomic explosion or a major accident (such as Chernobyl) and are therefore not necessarily suitable for holding against your Spitfire instrument to see how many Becquerel are being emitted. Take advice first and research it before clicking that ever-so tempting ‘Buy Now” button!

From a practical point of view I hope that the authorities – when they are made aware of the extent of the problem – and believe me they are watching us all the time – will be tolerant of Warbird operators, and providing the cockpit canopy is left open to allow the Radon gas to disperses, little else is required. Servicing the instruments though is another matter, and precautions will have to be met. In order to exceed the Act above, a licence will probably have to be obtained, unless the entire process is kept behind glass.

On a final note – do be aware that this is not the definitive word on the subject and this is a guide only – do the research first if you are concerned.