The RPB GX4, Model 08-400, tests the quality of compressed breathing air for Carbon Monoxide and other gases. The RPB GX4 when used with the Carbon Monoxide Sensor Cartridge (P/N: 08-420-01/08-420-02) satisfies the requirements of OSHA rule 29 CFR 1910.134 for carbon monoxide monitoring.. Check with your local regulatory bodies for more information on local requirements.