We ran a call for a man down to assist our local rescue squad recently. The man was running a propane powered floor cleaning machine in a business after hours. The rescue crew arrived and saw a man lying on the interior of the building with a "cloud" in the building. When we arrived we found 900 ppm CO. The worker was removed and treated (he later refused transport). We have recalibrated the monitor and RTS. My question is whether we should expect and sensor problems from the extremely high readings. Prior to this call, we had only experieced readings to approximately 250 ppm. The monitor is a Industrial Scientific 4 gas monitor. The vendor says that all is well as long as we keep it within calibration.