Good the see you reminding us about the carbon monoxide danger. I have a UEI COA2 sensitive CO detector that I have been carrying with me daily everywhere I go. Have been doing so for the last 4 years now. I have learned a great deal of what to expect for ppm readings in a wide variety of circumstances and locations. There is nothing like regular experience with an instrument to help you recognize when you encounter a situation where action is necessary. If you don't measure, you don't know. As an HVAC instructor for a Johnstone Supply I regularly conduct carbon monoxide classes. Now I have gone beyond that and combined teaching carbon monoxide safety and health with performing combustion analysis on furnaces. And, I use a UEI C161 combustion analyzer in the class with each student learning to perform an analysis in our own lab on our instructional furnaces. We combine some lecture with actual hands-on. With the heating season upon us this instruction is not just important but may save a life. Remember, CO not only is a potential killer, CO is often the source of many physical illnesses that are never traced back to CO as the cause. Meanwhile, some people suffer for years as the result of undetected CO poisoning.