This document applies to the BASIC SAFETY and ESSENTIAL PERFORMANCE of a HUMIDIFIER, also hereafter referred to as ME EQUIPMENT, in combination with its ACCESSORIES, the combination also hereafter referred to as ME SYSTEM. This document is also applicable to those ACCESSORIES intended by their MANUFACTURER to be connected to a HUMIDIFIER where the characteristics of those ACCESSORIES can affect the BASIC SAFETY or ESSENTIAL PERFORMANCE of the HUMIDIFIER. EXAMPLE 1 Heated BREATHING TUBES (heated-wire BREATHING TUBES) or ME EQUIPMENT intended to control these heated BREATHING TUBES (heated BREATHING TUBE controllers). NOTE 1 Heated BREATHING TUBES and their controllers are ME EQUIPMENT and are subject to the requirements of IEC 60601-1. NOTE 2 ISO 5367 specifies other safety and performance requirements for BREATHING TUBES. This document includes requirements for the different medical uses of humidification, such as invasive ventilation, non-invasive ventilation, nasal high-flow therapy, and obstructive sleep apnoea therapy, as well as humidification therapy for tracheostomy PATIENTS. NOTE 3 A HUMIDIFIER can be integrated into other equipment. When this is the case, the requirements of the other equipment also apply to the HUMIDIFIER. EXAMPLE 2 Heated HUMIDIFIER incorporated into a critical care ventilator where ISO 80601-2-12[12] also applies. EXAMPLE 3 Heated HUMIDIFIER incorporated into a homecare ventilator for dependent PATIENTS where ISO 80601-2-72[14] also applies. EXAMPLE 4 Heated HUMIDIFIER incorporated into sleep apnoea therapy equipment where ISO 80601-2-70[13] also applies. This document also includes requirements for an ACTIVE HME (HEAT AND MOISTURE EXCHANGER), ME EQUIPMENT which actively adds heat and moisture to increase the humidity level of the gas delivered from the HME to the PATIENT.