1. Hold the end of the strap with both hands, pull the strap completely so that the mask can completely cover the nose and mouth area, and connect the fasteners behind the neck to make the mask and face airtight. 2. Pull the end of the strap again to tighten it further. 3. Before use, check the mask to determine if it is properly sealed. 4. In the process of use, when the user smells the smell or the inhalation resistance increases, the service life of the filter box has expired, please replace the filter box or filter cotton immediately. 2. Special precautions for users 1. Please do not use this mask when the oxygen concentration is lower than 18%. 2. Please do not use in the following cases. Hazardous substances unknown Hazardous substances reach concentrations that immediately endanger life and health When you smell or taste harmful substances. 3. Pre-use training should be conducted by a qualified person before use. 4. When not in use, store the mask in a place away from contaminants and keep it sealed