Research commissioned by HMPPS found that the prison environment, including the condition of accommodation, played a role in how prisoners behave.20 Between 2015 and 2018, among adult prisoners, key indicators of poor safety in prisons reached all- time highs. This included a 110% increase in prisoner assaults on staff; a 63% increase in prisoner-on-prisoner assaults; and an alarming 73% increase in self-harm incidents. In addition, between 2015 and 2018, there were 378 self-inflicted deaths in prison custody.21 We heard from Professor Dominique Moran, who told us that records levels of self-harm and violence within prisons came at immense personal cost to the prisoners and staff involved, as well as carrying significant costs for the prison system.22