Cosmic Ray Simulation with PYTHIA

We present recent developments in PYTHIA for the modelling of hadronic cascades in a medium. Several improvements have been made in the Angantyr model for collisions with nuclei, especially in the limit of low collision energies, allowing it to be used throughout the hadronic cascades. Also the simplified nuclear model in the PythiaCascade} module has been updated. We find that the two models give consistent results for cosmic ray air showers initiated by both high energy protons and nuclei.