Short version: So you don’t get carbon monoxide poisoning. Long version: carbon monoxide is a by-product of the flames produced by many household appliances, like heaters, dryers, stoves, grills, and more. These appliances are designed to not overrun your home with CO fumes, but now and again, something goes wrong. And because carbon monoxide is a silent killer, without an alarm, you might not know what’s happening until it’s too late.