I'm a tad paranoid about home disaster preparedness, as my friends know based on my grab-and-go emergency backpack and how diligently I check my smoke and carbon monoxide detectors. That's why this news story has me so shaken up: It turns out that carbon monoxide detectors have an expiration date and writer Jeanne Sager learned about it the hard way.

Sager's house was protected by two CO detectors, one on each floor of her house, and she dutifully changed the batteries every two years, per instructions. But about six years after she bought her house, she started to feel exhausted all the time. Over the course of a couple of months, Sager found herself forgetting why she'd walked into a room, couldn't concentrate on work and lost her appetite.

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Soon after, Sager and her husband noticed soot near the heating vents in their home and called a repairperson. They discovered something totally terrifying. Their furnace had been leaking carbon monoxide into their home, and Sager had been exhibiting the classic symptoms of CO poisoning. The worst part is that through it all, their carbon monoxide detectors... never went off.

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Here's why: CO detectors actually need to be completely replaced every 5 to 7 years — not just have their batteries swapped out. Sager understandably didn't know this, and I'm pretty sure most people don't. Even in my own household prep paranoia, I've never heard this fact, nor have any of my landlords mentioned it. I just assumed that changing the batteries would keep the detectors in commission indefinitely.

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If you don't remember when you installed your home's carbon monoxide detectors, you should replace them immediately. It's a pretty minor, low-lift home improvement that could quite literally save your life. And don't forget to keep track of when they were installed so you know when to replace them next.

We don't mean to sound alarmist here, but you'll be able to (literally) breathe easier knowing you and your loved ones aren't at risk of a silent killer like CO poisoning.