Does natural gas kill?

November 16, 2005 11:51 AM

Does natural gas alone kill? I need someone to explain how natural gas becomes carbon monoxide and why my pet is dead.

I was out of the apartment last Thursday night when the pilot light on my oven went out. I came home in the morning to find the apartment filled with gas fumes and my sugar glider nearly dead. I have a carbon monoxide detector, and it was not going off. After taking my sugar glider to the vet (where she later died), I met with the gas company employee who could not detect carbon monoxide and insisted that natural gas alone is nontoxic. I know what happens to a human or animal when carbon monoxide is inhaled, but am not sure about the effects of natural gas. Is it possible that there was carbon monoxide built up from the gas leak that later dissipated and could not be detected by the gas company's equipment? Could I have died if I had been in the apartment overnight? I guess I'm dealing with the grief of this by focusing on the minutia, but seriously, what happened here?

posted by lunalaguna to health & fitness (25 comments total)

Any gas is toxic if it provides too much imbalance to the natural air you breathe. Even oxygen (it'll burn your lungs).

If enough natural gas was in the air, the concentration alone might be high enough that your pet was breating in more of that than air and suffocated.
posted by shepd at 11:58 AM on November 16, 2005

Natural gas is not carbon monoxide, so it won't set off your CO detector. But it is indeed toxic. That's why people stick their heads in the oven when they get enough of this cruel world. Sorry about your sugar glider.
posted by deadfather at 11:58 AM on November 16, 2005

Inhalation: Toxic by this route of exposure. May cause nausea, diarrhea, loss of appetite, dizziness, disorientation, headache, excitation, rapid respiration, drowsiness, labored breathing, anesthesia and other central nervous system effects. Hydrogen sulfide may cause lung paralysis and asphyxiation. Extreme overexposure may cause rapid unconsciousness and respiratory arrest.

posted by knave at 12:01 PM on November 16, 2005

The safety data sheet (MSDS) also says it's non-toxic.

But they also used to use canaries to detect gas in mines, and the reason was because they would die before the gas reached unsafe levels for humans. A source says the reason is that "the small size and high metabolic rate of birds increases their susceptibility to airborne toxins." It seems like a sugar glider would have the same exposures.
posted by smackfu at 12:01 PM on November 16, 2005

people stuck their heads in ovens when they used "town gas" (which contained carbon monoxide). natural gas kills by suffocation - it displaces the air you need - and by exploding.
posted by andrew cooke at 12:06 PM on November 16, 2005

ps your carbon monoxide detector is for detecting faults with faulty equipment that burns gas incorrectly.
posted by andrew cooke at 12:07 PM on November 16, 2005

Sorry to hear that your pet died. I had never heard of sugar gliders as pets - they look interesting.

Natural gas (CH4) is heavier than air, so if there was a leak, it would accumulate near the floor, forcing out air. The MSDS lists both methane and ethane as "Simple asphyxiant" - Your sugar glider probably suffocated, same as if it had drowned.

On preview, what andrew cooke said, minus the carbon monoxide part.
posted by GuyZero at 12:08 PM on November 16, 2005

Carbon monixide can be produced by the inefficient burning of natural gas. This is generally what the CO detectors monitor. A NG heating system is the usual culprit when CO levels are high. Of course, I once waved a cigarette at a CO meter (handheld, proffessional HVAC unit) and it went nuts. CO probably didn't kill your dog, it was the NG itself.
posted by IronLizard at 12:09 PM on November 16, 2005

Errr, not dog, what's a sugar glider?
posted by IronLizard at 12:10 PM on November 16, 2005

Sugar glider
posted by handful of rain at 12:12 PM on November 16, 2005

people stuck their heads in ovens when they used "town gas"

Thanks for the correction.
posted by deadfather at 12:13 PM on November 16, 2005

Natural gas, or methane only forms CO during combustion. The answers about suffocation are very much correct. Sorry about your sugar glider.
posted by frankie_stubbs at 12:14 PM on November 16, 2005

A sugar glider is a marsupial in the possum family. They are very popular exotic pets; you can find pictures and information about them at GliderNet. They are high maintenance, but make excellent pets as the bond deeply with their owners when taken care of properly. Luna was a very healthy, eight year-old glider that I have had since she was a few weeks out of pouch. I'm having a pretty difficult time with the loss and the circumstances surrounding her death.
posted by lunalaguna at 12:17 PM on November 16, 2005

I'm sorry about your loss, lunalaguna. What an awful accident.

A little natural gas may be relatively nontoxic. That is, you probably won't get sick from the fumes if your stove doesn't light right away. But natural gas in such quantities that it significantly reduces the proportion of oxygen in an enclosed space definitely puts you at risk of suffocation, not to mention fire. I don't know whether an extinguished pilot light could cause the buildup of a sufficient amount of gas to suffocate, but that's my best guess. It's very lucky that there wasn't a fire. The spark of a thermostat engaging could have ignited that gas.
posted by Songdog at 12:24 PM on November 16, 2005

I have no advice, I just wanted to say I'm deeply sorry about the loss of your sugar glider.
posted by agregoli at 12:30 PM on November 16, 2005

As andrew says, this is a matter of displacing air, not being toxic. Any gas that crowds out the oxygen living things needs can be fatal without actually being poisonous. Fire extinguishers that work with carbon dioxide or halon work through displacing oxygen since fires need oxygen too.

My condolences on your loss, but I am glad you and your home are okay.
posted by phearlez at 12:33 PM on November 16, 2005

Plus, of course, BOOM!
posted by briank at 12:45 PM on November 16, 2005

get your stove checked out....even if you were gone for days at a time, your pilot light should not be putting out enough gas that it would displace that much air.
posted by cosmicbandito at 1:18 PM on November 16, 2005

I'm sorry for you and for your pet. I've lost several over the years and it never gets easier.

Methane generally isn't thought of as toxic---every safety reference I can quickly put my hands on (the NIOSH guide, the ACGIH TLV and BEI guide, the Environment Canada First Responder's Guide, a bunch of MSDSs) all list it as an asphixiant only. That generally includes most mammalian species, but small animals with fast metabolisms can be more susceptible to exposure than humans (which is what all my guides are written for). Danger from asphixiants is easily checked by measuring for oxygen level. The lowest safe level for oxygen is considered to be about 19.5% (21% is normal). Again for small mammals, this might be different.

CO, by contrast, is quite toxic. It causes acute damage, effectively killing red-blood cells. It is not usually thought to have long-term effects (like cancer or liver damage) to any great degree (though reduction in oxygen transport can cause longer term problems all on its own). For humans, the highest long-term exposure level (the TWA/TLV) is 25 ppm. Most household CO monitors are set to trigger well below that value. If you're concerned, you might check yours. Again, the sad fact of the matter is that small animals with high metabolisms will probably be more sensitive than you are.

CO is (almost) always caused by poor combustion. Badly adjusted stoves, furnaces, dryers and water heaters are the usual culprits, but living near or on a busy thoroughfare or in other high traffic areas can cause problems too. Idling (poorly tuned) engines can be a real problem for CO generation.
posted by bonehead at 1:46 PM on November 16, 2005

What cosmicbandito said. Even though sugar gliders are wee compared to people, pilot lights aren't supposed to put out that much gas.
posted by desuetude at 1:52 PM on November 16, 2005

A few years ago, I got really sick with fatigue, lethargy, dizziness, etc. Doctor couldn't figure out what was wrong for several weeks. I had a carbon monoxide meter that never showed abnormal levels. Eventually, someone who visited my apartment noticed a smell of natural gas. The pilot light wasn't out, so I called the gas co. and they came to check it out, and discovered the stove was leaking gas. I had the landlord fix the stove, and I got better within a couple days.

I don't think enough gas could come out of a regular stove to kill a human, at least not in one overnight. I became ill over time, not all at once, and there was a significant leak from my stove.

I am guessing that natural gas in the air would have more of an effect on a tiny animal than on a large human. Or perhaps certain animals react to natural gas differently.

Very sorry about your pet. It's just one of those freak things that happens sometime, there's nothing you could have done to prevent it.
posted by clarissajoy at 2:00 PM on November 16, 2005

No advice to give, but really, really sorry to hear about Luna.

/ lost a cat, Loki, that I had raised from a kitten a month ago
// sniff
posted by LordSludge at 2:11 PM on November 16, 2005

Natural gas (CH4) is heavier than air.

No, it's not. At a given temperature and pressure, the density of a gas is proportional to its molecular weight. Natural gas (about 95% methane, CH₄, MW=16) is lighter than the atmosphere (primarily N₂, MW=28, and O₂, MW=32).

Propane, on the other hand (C₃H₈, MW=44), is heavier than air, and it bugged me to no end when they got that wrong in Panic Room.
posted by DevilsAdvocate at 2:45 PM on November 16, 2005

By the way natural gas does not have an odour by itself. The only reason you can smell it is because the gas companies put in a very smelly compound called a thiol - related to the chemical skunks spray.
posted by rongorongo at 4:32 PM on November 16, 2005

This is why I got a got a CO / CH4 / propane detector (and DevilsAdvocate is correct -- CH4 is lighter than air).

(I lost a fish yesterday)
posted by dirigibleman at 9:30 PM on November 16, 2005