Turned out the poor fella just had a case of long-term carbon monoxide exposure. He was leaving himself notes. He just couldn’t remember it because of the CO he’d been breathing. He’s lucky that he came out of it with nothing worse than a creepy tale, because carbon monoxide is deadly. At Reviews.org, we recommend always having a working carbon monoxide detector in your home to protect you and yours. But … how do they even work? It’s not what humans breathe out—that’s carbon dioxide. (One extra atom of oxygen makes all the difference.) Carbon dioxide isn’t great for humans, either, but it doesn’t come out of major household systems and appliances the way carbon monoxide can. 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. Symptoms can include:

HeadachesWeaknessDizzinessNausea/vomitingShortness of breathConfusionBlurred visionUnconsciousness

Some folks who have carbon monoxide poisoning make a full recovery. But for some, there can be long-term effects, such as:

Miscarriages and stillbirthsPermanent brain damageHeart damageDeath¹

How sick you get and whether you make a full recovery depends on a few factors, like how much CO you breathe and for how long. If you believe you have carbon monoxide poisoning, seek fresh air, then get medical treatment. But the easiest, surefire way to know you’re suffering from CO poisoning? A working carbon monoxide detector. With an alarm to warn you before you start feeling too sick, you’re also less likely to suffer long-term effects. An electrochemical carbon monoxide alarm uses electrolytes for its early warning system. When carbon monoxide touches the electrolyte, a chemical reaction sets off the alarm. An alarm that uses a metal oxide semiconductor depends on electrical circuitry. The contact with carbon monoxide completes a circuit that sets off the alarm. Finally, a biomimetic sensor uses gel that mimics the hemoglobin in your blood. If the gel absorbs too much CO, the alarm goes off. Cool, right? We think it sounds like something from a sci-fi novel, but it’s 100% real.² Regardless of the tech used, all three types will sense a carbon monoxide leak long before you’re in danger. Also, think hard about what types of detectors you need and where. Because CO rises, most folks opt for hardwired or battery-dependent ceiling installs. But that doesn’t mean you can’t use a plug-in model; you’ll just want to think hard about when and where to place it. If you buy a portable, battery-based detector, you just need to pop in some batteries, set the detector in your room of choice, and then run any required tests. If you buy a plug-in detector, you only have to plug it in, then test it. But if you’re buying a detector that goes on the ceiling, it’s a little more complicated. We’re no electricians, so we can’t take you on a step-by-step (although your alarm instructions should be able to). But here’s a general idea of steps you’ll likely take. Not for the faint of heart, especially when it comes to wiring. If you don’t have much electrical experience and don’t feel comfortable attempting the wires, ask someone more knowledgeable to do it for you.

Why do you need a carbon monoxide detector? To warn you about carbon monoxide poisoning. How does a carbon monoxide detector work? There are various ways, but in the end, they all provide early warning about the dangers of carbon monoxide gas. Which carbon monoxide detector should I choose? Whichever one best suits your needs. How do you install a carbon monoxide detector? It varies, but keep in mind that a wired installation is not for everyone.