A damning inspection of Dartmoor Prison has criticised the time taken to act over high levels of radon detected four years before all prisoners were finally evacuated from the Category C prison.

The annual report by the Independent Monitoring Board (IMB), published in the last few days, asks why it took the prison authorities two years to begin work after radon levels were found to be unacceptably high in 2020.

The IMB reports that although elevated levels of radon gas were detected in the prison in 2020, posing potential health risks, administrative delays meant mitigating action did not begin until 2022.

The situation reached crisis point in late 2023, high radon levels prompted the decanting of prisoners from affected wings, disrupting the operation of the prison and displaying vulnerable inmates just before Christmas.

Ventilation issues in 2024 worsened the situation and inconsistent radon readings created anxiety among prisoners. As the number of prisoners in Dartmoor declined, the infrastructure deteriorated, further complicating mitigation efforts.

Conflicting orders from the Prison Service and Health and Safety Executive led to the repeated decanting and recanting of prisoners, the IMB found.

High radon levels in wing atriums finally led to the prison’s temporary closure, with all prisoners and staff transferred out by August 2024.

The long-term future of the prison remains in doubt. There is concern from locals as the prison is a major employer.

Chair of the Dartmoor IMB, Jo Wymer, said: “The future of HMP Dartmoor remains uncertain, with reopening contingent on mitigation plans and funding. As the prison’s population was reduced and staff deployed elsewhere our monitoring highlighted the infrastructure decay and showed the urgency for a resolution. Now the prison only has a skeleton staff left, the fabric of the buildings will only deteriorate further.

She added:"The closure of HMP Dartmoor has taken some 650 places out of the national estate, led to prisoners and staff being dispersed around the country, and a local community and economy uncertain as to what might happen. The Prison Service and the Ministry of Justice need to make an urgent decision on the prison’s future and communicate that decision as soon as possible so plans can be made for moving ahead.”