Carbon monoxide
A gas you cannot see or smell, from anything that burns fuel. An alarm is the only thing that will tell you it is there.
Draft — not yet medically reviewed
Emergency possible
If this is happening now
This information is not a substitute for talking with your child's doctor.
Poison emergency? Call Poison Help at 1-800-222-1222.
Here in our region
In the mountains, carbon monoxide poisoning looks almost exactly like altitude sickness — headache, nausea, dizziness, feeling wiped out. That resemblance is a real trap for visitors and locals alike, and it is worth knowing before you need it.
Alarm laws differ across our six states. Colorado's Lofgren and Johnson Families Carbon Monoxide Safety Act (2009) requires alarms, but only when a home is sold or transferred, altered under permit, gains a new bedroom, or changes tenants — so plenty of occupied homes have none. Montana requires them in rentals. North Dakota's code requires interconnected alarms on every habitable level. Utah's requirement applies to new construction. For South Dakota and Wyoming we could not confirm a statewide requirement. Install them regardless of what your state requires.
Why you cannot detect it yourself
Carbon monoxide has no colour, no smell and no taste. It comes from anything that burns fuel — a furnace, a water heater, a wood stove, a gas range, a generator, a car engine, a camp stove.
Once you breathe it in, it takes the place of oxygen in your blood. There is no way to sense it without an alarm.
Who is most vulnerable
Everyone in the household, but children and anyone pregnant are more vulnerable — children breathe faster and take in more for their size. Pets often show it first.
It looks like the flu, or like altitude sickness
Headache, dizziness, nausea, confusion, weakness, unusual sleepiness.
Two clues that it is not a virus:
- More than one person — or a pet — feels ill at the same time
- Everyone feels better after being outside, and worse again indoors
If you are at elevation, do not assume it is altitude. The two are very hard to tell apart.
Five things, and the first one matters most
- Put alarms on every level of the home and outside sleeping areas. This is the single most effective thing on this page.
- Test them. CDC suggests using the clock changes in spring and autumn as your reminder.
- Have the furnace, water heater and any wood or gas stove serviced once a year.
- Never run a generator, grill, camp stove or heater indoors — and that includes a garage, a tent, an ice-fishing house or a camper.
- Never warm up a car in an attached garage, even with the door open.
This one is an emergency
If an alarm sounds, or more than one person or pet has symptoms: get everyone outside into fresh air and call 911.
Do not go back in to investigate, open windows or find the source. Let the fire department do that.
If you are unsure whether an exposure happened, call Poison Help at 1-800-222-1222 — 24 hours a day, free.
“The alarm went off but we all feel fine.”
Treat it as real anyway. Leave the house and call for help.
Alarms do fail and batteries do chirp, but you cannot tell the difference from inside the building — and the whole reason the alarm exists is that your senses cannot detect this gas. There is no downside to being wrong about a false alarm.
Resources
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Show the clinical text of this topic
The short version
- Pulse oximetry reads falsely normal in carbon monoxide poisoning. You need co-oximetry.
- Venous blood is acceptable for carboxyhaemoglobin — an arterial stick is not required.
- Oxygen given before the draw invalidates the level. Document the time oxygen started.
- The pediatric COHb threshold commonly cited for significant poisoning is 15%, against 20% in adults.
- Treat with 100% oxygen. Consider hyperbaric oxygen at higher levels or with neurological findings — sources differ on the exact cut-off, so treat it as a consult decision rather than a fixed rule.
Practical points
Assess everyone in the household, including pets if the history mentions them — an index case usually is not the only one exposed.
Take an exposure history that covers heating source, generator use, attached garage, recent power outage, and any camp stove or heater used in an enclosed space.
Altitude, and what nobody has settled
- Altitude adds to the insult. The hypoxic effects are additive, and carbon monoxide poisoning mimics acute mountain sickness closely enough to create a genuine anchoring hazard in mountain communities. This is verified qualitatively only.
- No altitude-adjusted COHb thresholds exist. Do not imply one.
- Whether standard UL 2034 alarms perform accurately above 5,000 feet is unresolved in what we could verify. It does not change the advice to install them.