In the chaotic archives of internet history, few threads carry the weight of the reddit carbon monoxide story. It sounds like the opening scene of a psychological thriller. A guy wakes up and finds a yellow Post-it note on his desk that he doesn't remember writing. Then another one appears on his chair. Then more on his door.
Most people would assume they’re being stalked. That’s exactly what the original poster, a user named u/RBradbury1920, thought was happening back in May 2015. He turned to the r/legaladvice subreddit, convinced his landlord was breaking into his narrow, windowless apartment to leave him creepy reminders.
When "Stalker" Notes Turn Out to Be Your Own Handwriting
The initial post was frantic. The user described finding notes in a handwriting that "wasn't his," reminding him of errands he’d never told anyone about. He even set up a webcam to catch the intruder, but the footage would mysteriously disappear or the recycling bin on his computer would be emptied.
Honestly, the comments were a mess at first. Some people told him to call the police immediately. Others thought he was sleepwalking. But then, a user named u/kakkerlak (Ken Roach) stepped in with a suggestion that seemed completely out of left field: "You might have a carbon monoxide leak."
It was a brilliant, life-saving hunch. Roach noticed two specific details: the OP mentioned his bedroom had no windows, and his "evidence" was increasingly nonsensical.
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Carbon monoxide (CO) is often called the "silent killer" for a reason. You can't smell it. You can't see it. But as it builds up in your bloodstream, it replaces the oxygen in your red blood cells. This leads to cerebral edema, or brain swelling, which causes massive confusion, memory loss, and—as we saw here—complex hallucinations.
The Update That Broke the Internet
Following the advice, the OP actually went out and bought a CO detector. He didn't even have to wait long. As soon as he plugged it in, the thing started screaming.
The levels in his apartment were at 100ppm. To give you some perspective, that's a concentration high enough to cause significant physical symptoms after just a few hours of exposure. He wasn't being stalked by a landlord; he was being poisoned by his own home. He had been writing those notes to himself in a dissociative state and then completely forgetting the act seconds later.
The "intruder" was just his own hand.
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What happened next?
- Hospitalization: The OP was rushed to the emergency room.
- The Cause: It turned out the leak was coming from the building's internal parking garage located directly beneath his floor.
- Recovery: In an update posted ten months later, he admitted the recovery was slow. He suffered from headaches and "brain fog" for a long time.
- Legal Action: He eventually reached a settlement with the landlord regarding the unsafe living conditions.
There’s a bit of irony in his username, too. Ray Bradbury wrote sci-fi stories that often dealt with memory and the distortion of reality. Some skeptics on Reddit still claim the whole thing was a "creepypasta" or a hoax because the narrative was just too perfect. They point to the fact that 100ppm is a "thin line" between hallucination and death.
However, medical experts, including Dr. Tom Scammell from Boston’s Beth Israel Deaconess Medical Center, have noted that while writing coherent sentences while "sleepwalking" is rare, the cognitive disruption caused by CO poisoning makes it entirely possible to perform "automatic" tasks without retaining the memory.
How to Tell if You’re "The Reddit Guy"
If you're reading this and feeling a sudden twinge of paranoia about your own apartment, take a breath. But also, take action. This story isn't just a piece of internet lore; it's a massive PSA for home safety.
Don't wait for "ghosts" or mysterious notes. CO detectors are cheap. You can get one for twenty bucks at any hardware store.
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Warning signs of a CO leak:
- Persistent headaches that only seem to happen when you're at home.
- Unexplained fatigue or feeling "flu-ish" without a fever.
- Nausea and dizziness that clears up when you go outside for fresh air.
- Confusion or memory gaps (the Post-it note stage).
If your detector ever goes off, don't ignore it. Don't assume it's a low battery. Get out of the house, leave the door open to vent, and call the fire department.
Staying Safe Moving Forward
The legacy of the reddit carbon monoxide story is that it basically turned the r/legaladvice community into amateur CO detectives. Now, whenever someone posts a story about "missing items" or "hidden cameras" with no proof, the top comment is almost always "Check your CO detector."
It’s a weirdly wholesome part of the internet where a random engineer's comment likely saved a stranger’s life.
Actionable Steps for Your Home:
- Install a CO detector on every level of your home, especially near sleeping areas.
- Replace the batteries every six months (do it when you change your clocks for Daylight Savings).
- If you live above a garage or use gas appliances, be doubly vigilant about ventilation.
- Check the "end of life" date on the back of your current detector; most only last 5 to 7 years before the sensor fails.
The human brain is incredibly fragile. Sometimes, what we perceive as a haunting or a conspiracy is just a chemistry problem in the air we breathe. Keep your sensors active and your batteries fresh.