CIH calibrates and verifies the performance of indoor air quality instruments & gas monitors. A full calibration goes a step farther than a functional bump test and ensures maximum accuracy of the instrument if performed successfully. Using a known comparison of test gas, the meter reading is compared to the actual concentration of the gas and then adjustments are made to the readings if they do not match. If a sensor fails calibration, it should be replaced and the instrument must be re-calibrated. Recently, OSHA published a bulletin specifically addressing the need for regular calibration of direct reading gas monitors. Although it is not a standard or regulation, the bulletin is a clear recommendation to follow guidelines put forth in the position statement released by the International Safety Equipment Association (ISEA) on instrument calibration for gas monitors used in confined spaces.