New radon regime at HMP Dartmoor as inmates return

A new regime ventilation and testing is under way at HMP Dartmoor

New daily ventilation measures are under way at HMP Dartmoor as prisoners are being returned after an investigation was launched into high levels of radioactive radon gas found at the jail.

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

It is understood 30 prisoners a week are due to be returning to the site, amid a "new regime" to open all roof vents, windows and doors three times a day in impacted areas in order to "purge" radon gas.

A Prison Service spokesperson said: “Prisoners will 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."

'Appropriate mitigations'

It added: “We continue to engage closely with the Health and Safety Executive and we will regularly review the situation.”

It is understood the Ministry of Justice (MoJ) has put in place "appropriate mitigations" which have been agreed with the HSE.

These include a "new regime" of purging, alongside a regime of "live testing" radon levels in a number of cells.

They also include opening windows, doors and roof vents three times daily.

Prisoner transfers back to Dartmoor recommenced on 1 July, the MoJ said.

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 (FoI) 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.

The gas caused about 1,000 lung cancer deaths in the UK every year, the security agency said.

More than 300 prisoners and former inmates are understood to have sought legal counsel over their potential exposure.

An HSE spokesperson confirmed their investigation was ongoing.

They said: “We have written to His Majesty’s Prison and Probation Service (HMPPS) informing them of legal requirements relating to radon exposures. The legal duty to keep prisoners and staff safe rests with HMPPS.

“However, our investigation is ongoing and we cannot comment further at this time.”