[en] The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is a multilateral agreement that prohibits any nuclear explosion, whether for military or civilian purposes. The treaty is supported by a network of International Monitoring Systems (IMS), including radionuclide monitoring stations. Malaysia is the Member State of CTBT and hosts the Radionuclide Monitoring Station (Location Code: RN42) in Tanah Rata, Cameron Highlands, Pahang. Continuous daily measurements at RN42 have been an invaluable resource for understanding the variation of natural radioactivity in that area. This study analyses radionuclide measured at the surface air in Tanah Rata, Cameron Highlands, Pahang via RN42 station in 2020. The results show that most of the radionuclide measurements in RN42 are categorised as a natural background. However, throughout 2020, the station has several times measured radionuclides with anomalous concentrations. The significant findings may form the basis for further studies on local radiological impact assessment as well as the development of baseline radiological data. (author)