Inmates return to HMP Dartmoor as prison implements 'new regime' to remove radon gas

HMP Dartmoor opened in 1809 and was set to close in 2023, but the plans were scrapped. Credit: PA

Inmates who were transferred from a prison after high levels of radioactive gas were detected are being returned.

Hundreds of prisoners were moved from HMP Dartmoor, in Devon, after the Health and Safety Executive (HSE) launched an investigation into radon exposures at the site in December 2023.

It is understood that 30 prisoners are due to be returning to the site each week, amid of "new regime of purging radon gas" from affected areas.

A Prison Service spokesperson said: "Prisoners will be gradually returned to HMP Dartmoor following conversations with the Health and Safety Executive and we have ongoing mitigations in place to limit radon exposure."

"We continue to engage closely with the Health and Safety Executive and we will regulalry review the situation," they added.

HMP Dartmoor in Devon is in an area with high concentrations of granite. Credit: PA

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

The MoJ said HMP Dartmoor will be implementing a "new regime" of purging gas in the atmopshere by opening windows, doors and roof vents three times a day.

These new ventilation measures will work alongside a regime of "live testing" radon levels in several cells, the MoJ said.

It added prisoner transfers into HMP Dartmoor recommenced on 1 July 2024.

Radon, an odourless and colourless gas, is produced by decaying radioactive materials in rocks and soils, and is responsible for around 1,000 lung cancer deaths a year.

It is thought to occur more often in areas with high concentrations of granite, such as Dartmoor.

An HSE Executive confirmed that an investigation into radon exposures at the Category C prison is ongoing.

"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," an HSE spokesperson said.

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

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