Radiological protection requirements with regard to cosmic ray exposure during air travel Cebastien Joel Guembou Shouop, Maurice Ndontchueng Moyo, Eric Jilbert Nguelem Mekongtso, Kunwoo Cho and David Strivay Eur. Phys. J. Plus, 135 5 (2020) 438 Published online: 27 May 2020 DOI: 10.1140/epjp/s13360-020-00468-8