Niall is a public health physician in Dublin, Ireland, specialising in communicable disease outbreak control in a busy regional health protection unit. He is also Adjunct Professor of Public Health Medicine at University College Cork, Ireland. He has worked extensively in paediatric global health, with stints in Sierra Leone, Somalia, Nepal and Ukraine. Niall has been most closely associated with Sierra Leone, where he spent a long time working at Bo Government Hospital. Firstly, in 2013 in the children's ward and secondly in 2017, when he returned to establish the region's first neonatal treatment unit. Niall is currently part of Project Bo, which is aiming to use sustainable solar power to provide 24-hour electricity to the newborn unit at Bo Government Hospital.