The EQF3320 can measure the activity concentrations of radon and thoron and their short-lived decay products from the same air sample. Unlike the EQF3300, the two size fractions relevant for dose assessment are determined separately. Sampling takes place via the wire mesh on the front of the measuring head. In this process, the atomic (free or unbound) decay products are completely deposited on the wire mesh. The decay products already bound to larger aerosols (attached) can follow the air flow unimpeded and are collected on a filter at the rear of the measuring head. Semiconductor detectors are positioned above the wire mesh and filter to determine the respective deposited activities. The intake area and mesh size of the wire mesh have been maximized to minimize deposition losses and prevent the mesh from becoming blocked by dust. The filter and wire mesh are easily accessible and can be replaced without tools. The measuring head is detachable from the device. The air sample enters the device’s radon measurement chamber via the connecting hose. The spectroscopic measurement method offers the shortest response and decay times and prevents progressive contamination of the measurement chamber by 210Po. Thanks to the special design of the four measuring chambers, sensitivity remains constant even at high humidity levels, eliminating the need for a desiccant cartridge. The device records environmental conditions, operating states, and relevant events. A flexible alarm system allows users to implement their own warning and alarm functions. Additional sensors can be connected to the accessory port on the front panel. The integrated GPS receiver provides the corresponding measurement location for map display in the dVISION operating software. The large, bright color display with intuitive touch menus offers modern ease of use and access to all relevant information. With its configurable digital and analog interfaces, the device can be integrated into any network. The EQF3320 is manufactured entirely at our company location in Dresden and calibrated in our DAkkS-accredited calibration laboratory. Only high-quality components are used in the device, and thanks to its design and material selection, the EQF3320 is nearly 100% recyclable.