Reflections in Kibera slum, Nairobi, Kenya: Hossein Fatemi’s best phone picture

The poverty I saw really shocked me, but also the people I saw were happy, they were friendly, they were sharing'

The trip Hossein Fatemi made to Somalia in 2011, on assignment for an Iranian organisation, marked a turning point in his career. The New York-based photojournalist had covered many serious situations, but what he saw in Mogadishu - thousands of children dying in desert hospitals, without food or water, without anything" - is something, he says, that he will never forget.

Fatemi returned to east Africa the following year with a group of Iranian photographers to focus on the lives of the refugees fleeing not only the conflict but also the drought and the flooding. He shot only on his phone because it puts people at ease. Most of my colleagues would not risk relying solely on their phones," he says, but it gave me more flexibility and lent a more natural feel to the images."