This category includes systems with room terminals equipped with a fan (fan coils, fan-powered terminal boxes, VRF – VRV systems), systems with chilled beams, radiant systems or any other system with recirculation in the single room. This recirculation depends on air movement induced by the fan, and on the flow of outdoor air in active chilled beams. In radiant systems, it is a function of their share of convective exchange, which can reach 50% in radiant floors in heating, and with radiant ceilings in cooling. Not all terminals are able to filter the air effectively.  In any case the ‘normal’ air filters used in this system are unsuitable to filter the aerosol, which is characterized by an order of magnitude of tens of nanometres. Furthermore, for both ‘normal’ filters and other particulate filters, there is currently no evidence regarding the filtration efficiency of these filters with regards to SARS-CoV2-19. Thus, at present there can be no distinction between different terminals. Whatever the type of system, it is not necessary, or productive, to stop the operation of the terminals because the risk of contagion remains unchanged.