An AX filter is a type of protective filter for respirators and half masks, designed to protect against organic gases and vapours with a low boiling point, specifically up to 65 °C. Such substances include, for example, acetone, methanol, or dichloromethane. Unlike the more common „A“ type filters, which are intended for substances with a higher boiling point, the AX filter is specifically engineered for these more volatile compounds. For safety reasons, it is designed exclusively for single use and must not be stored for repeated deployment. The reason is the risk of so-called desorption, where captured substances can spontaneously release from the filter back into the surroundings, causing the filter to lose its protective function.