Only a proportion of magmatic gases are released from the crater and form the volcanic plume. A significant proportion diffuse through the wall of the magma chamber and conduit and can later be measured within the soil of the flanks of the volcano. A map is being created of CO2 and Rn concentrations over the edifice. This will indicate regions of enhanced degassing, generally represented by faults. Monitoring of the temporal variation the diffuse degassing can give an indication of the movement of a magma body. Periodic measurements of CO2 have been made and a couple of locations. A solid-state probe has been installed to measure the fluctuation in Rn concentration. Additionally, a monitoring site using plastic track-etch detector has been established at La Lumbre. The detector is changed every month and upon processing gives the integrated Rn concentration at this point.