This is a carbon monoxide detector held at about mouth level above an operating oven. The general guidelines are for variously 9ppm, 30 ppm, or 50ppm as the cut off levels for human health. In this example, if you were baking an eggplant Parmesan while stirring your pot of fettuccine, you would also be sucking down 94 ppm of hemoglobin-suffocating carbon monoxide. Luckily, these folks have a vented kitchen fan, which they use when they bake.