Review on UEi Test Instruments CO71A Handheld Digital Carbon Monoxide Detector, Portable CO Meter with 0-999ppm Range, Visual and Audible Alerts, CO Monitor Tester + Battery Included by Jeff Grindley

Although these things are expensive, they are worth every penny. After much research I realized that my baby carbon monoxide detector is only useful to sound an alarm when it exceeds 30ppm. Should be 10ppm. You can get readings as low as 1ppm with these good portable models. You will know how much of your breath. I installed a fanless fireplace and wanted to know. It toggles between 0 and 1ppm. Peace of mind is worth it.