Dartmoor prison to temporarily close due to radon

Moving the convicts starts on Thursday, with 40 inmates being moved at a time, prison officers say

HMP Dartmoor is to close temporarily, with all inmates to be moved out, the Ministry of Justice (MoJ) has said.

The department said it followed the discovery of high levels of radon at the jail.

The MoJ said there was enough capacity in other prisons for the inmates, who number about 175 at the jail, despite concerns about overcrowding.

A spokesperson for the department said: "Our prisons are in crisis. This is the most recent illustration of why this government was forced, in its first week, to take urgent action to release pressure on the estate."

A map showing radon levels in England. The darker the colour, the greater the chance of a higher level

The Prison Officers Association (POA) said the process of moving inmates would start on Thursday, with 40 prisoners moved at a time, and the aim was for all cells to be vacant by the end of the July.

More than 400 prisoners were moved from the Devon prison after the Health and Safety Executive (HSE) launched an investigation in December 2023.

The HSE said it had been told by HM Prison and Probation Service about the "decision to temporarily close the prison".

It comes on the same day the government laid regulations in Parliament to reduce the amount of time prisoners must spend in jail before they are automatically released from half of their sentence to 40%.

The move, which does not apply to those convicted of sex offences, terrorism, domestic abuse or some violent offences, follows a speech by Justice Secretary Shabana Mahmood in which she warned failing to take action would result in the "collapse" of the prison system.

Peak radon levels

A Prison Service spokesperson said earlier this month the prisoners would be "gradually returned to HMP Dartmoor following conversations with the Health and Safety Executive as we have ongoing mitigations in place to limit radon exposure".

Prisoner transfers back to Dartmoor recommenced on 1 July, the Ministry of Justice said at the time.

Peak radon levels detected at HMP Dartmoor in 2020 and 2023 were 10 times the recommended workplace limit, according to the response to a Freedom of Information request submitted by the BBC.

Radon is a colourless and odourless radioactive gas formed by decaying uranium found in rocks and soils.

Levels may be higher in parts of the country rich in granite, such as Dartmoor, according to the UK Health Security Agency.

Built in the early 19th Century to hold French prisoners during the Napoleonic Wars, HMP Dartmoor had been slated for closure in 2023, but that decision was reversed in 2019 in the face of rising prisoner numbers.