The polonium traces in the investigation into the death of Mr. Litvinenko were found to be Polonium-210 (Po-210). It occurs naturally and is present in the environment and in people at very low concentrations. It can also be made by irradiation of other materials. Polonium-210 has a half-life of 138 days. It undergoes decay by emitting alpha particles, accompanied by very low intensity gamma rays.
Polonium-210 can only represent a radiation hazard if it is ingested, inhaled or otherwise taken into the body—for example, through an open wound. Where patches of contamination have been discovered in public places these have equated to polonium that weighs less than one millionth of a millionth of a gram—hence they are so low to cause no concern to immediate or longer term health.
Police officers and the NHS Ambulance Service undertaking all activities in the death of Mr. Litvinenko are working to the principle of as low as is reasonably practicable (ALARP) and in addition are working to a maximum radiation dose constraint of 1 mSv. This is the legal limit of exposure for members of the public as defined under the Ionising Radiation Regulations 1999. Though legislation and best practice allow higher dose limits for emergency activities and employees, setting this lower constraint level ensures that the risks to emergency workers are kept low.
The Fire and Rescue Service (FRS) had no operational involvement in this case. In the case of an accidental release of polonium FRS personnel would be engaged only after a full assessment of the level of release had been made and specialist radiological advice obtained. Firefighter operations in the contaminated area would be restricted and those likely to be exposed would be equipped with appropriate personal and respiratory protective equipment. This and associated control measures adopted by the FRS would aim to protect staff from accidental release of Polonium-210.