Results are presented on measurements of particle confinement in JET using trace amounts of tritium, in the presence of m=3, n=2 magnetic islands induced by Neo-classical Tearing Modes (NTMs). 3/2 NTMs are generally correlated with an energy confinement degradation of ~10-20% and this is understood as being due flattening of the pressure across the magnetic island. The recent JET trace tritium campaign allowed us to study the influence of the NTM on particle transport, from the observed evolution of the 14MeV neutron emission profile following puffs of trace amounts (2.5 to 5mg) of tritium.