Standardisation of the particular requirements for basic safety and essential performance of medical devices and their accessories intended for ventilatory support, delivery of respiratory gases and related monitoring of patients. This includes dosing and conditioning of the gases supplied to or inhaled by the patient. These medical devices can be intended for use in specific, particular or defined healthcare environments, including home healthcare environments. These medical devices are generally active, reusable electromedical equipment (i.e. durable) with accessories that mainly are for single-patient use. ISO/TC 121/SC 3 is also responsible for the biological evaluation of gas pathways in all environments. Further, ISO/TC 121/SC 3, in co-operation with IEC/TC 62 Subcommittees utilizing Joint Working Groups, is responsible for the standardisation of the horizontal requirements for basic safety and essential performance of medical electrical equipment used in: