Stepping out from a bloody field hospital onto a street ruined by Russian and Syrian airstrikes, Dr Abdulsalem smiles wearily: "This is the first time in a month that we have gone outside". A ceasefire has given a rare moment of rest in the otherwise relentless siege of Aleppo. Working constantly since the outbreak of the war, Dr Abdulsalem spends day and night treating a heavy and continuous flow of casualties. Many of them are civilians: women and children maimed by regime bombing. "They strike in neighbourhoods where there are only civilians, no fighters", he says. Though determined to stay in Aleppo as long as he is needed, the horror of what he encounters on a daily basis has had a traumatising effect on him: "Sometimes I close my door and break down in tears because of what I have seen"