The half mask is only used for certain concentrations of harmful substances in the environment. Use in unknown or hazardous atmospheres is not permitted. In activities involving open flames or liquid metals, there is an increased risk of the filter performance being impaired by activated carbon. Furthermore, the mask must not be used in oxygen-deficient environments with an oxygen content of less than 19.5 % or in oxygen-enriched environments with an oxygen content of more than 25 %. Use of the filters is not permitted if the CO₂ concentration exceeds a value of 0.1 % vol. Modifications to the device may impair certification and protection. The service life of the filters is limited. Due to specific facial features, such as beard growth, it cannot be ruled out that the correct fit of the mask may be impaired. With regard to disposal, it should be noted that this must be carried out in accordance with the relevant regional regulations. The manufacturer accepts no liability for damage caused by improper use.