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According to the CDC, you should "NEVER use a gas range for heating".

Never use a gas range or oven for heating. Using a gas range or oven for heating can cause a build up of CO inside your home, cabin, or camper.

Is this valid advice though? Is there any evidence that a gas range not used for cooking is a danger to the household when only burning gas with an open flame? If so, how many hours of use is required for this danger to manifest?

And also the EPA provides similar guidance,

Using a stove hood with a fan vented to the outdoors greatly reduces exposure to pollutants during cooking. Improper adjustment, often indicated by a persistent yellow-tipped flame, causes increased pollutant emissions. Ask your gas company to adjust the burner so that the flame tip is blue. If you purchase a new gas stove or range, consider buying one with pilot less ignition because it does not have a pilot light that burns continuously. Never use a gas stove to heat your home. Always make certain the flue in your gas fireplace is open when the fireplace is in use.

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    You seem to have answered your own question. – Schwern Feb 18 at 3:40
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    Yes, it is valid advice that you should never do that. Sure, there are plenty of cases when people will survive (even without repercussions) even when doing something dangerous/stupid. That does not invalidate a claim that "you should never do it". There are people who survived falling out of airplane without parachute. Still, it is valid advice that "you should never jump from airplane without parachute". Same here. – Matija Nalis Feb 18 at 16:05
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    Curious why you'd think both the CDC and EPA would put out incorrect information about this. I'd say those are about as trustworthy a source as any. What source would you accept over those two? What about D.C.'s government page? Have you found a source saying it's not dangerous? – BruceWayne Feb 18 at 22:07
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    @JSLavertu, efficiency is generally not the primary consideration when the alternative is freezing to death, which is generally the sort of situation where people start considering stuff like this. – Nate S. Feb 18 at 23:17
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    This seems like a perfect example of when a harm reduction approach should be used, instead the CDC advocates abstinence approach under the misguided idea that if you withhold information people won't do the thing you don't want them to do. This is completely incorrect-- people do the thing anyway, but without any knowledge whatsoever instead of making informed risk-choices. When people do resort to this it's, as @NateS says, because the alternative is also quite bad. It's easy to say never do this if you've never lived in an apartment where the heat was out for days to weeks on end. – eps Feb 19 at 1:26
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Yes, because the safety systems that are required for furnaces and water heaters are not standard on stoves and ovens.

Conventional gas-burning furnaces and hot water heaters include two design elements to prevent build-up of carbon monoxide (poison hazard) and natural gas (explosion hazard) inside the house:

  1. A flame sensor checks if the gas is burning. If it is not, the gas valve closes. This way, if the flame is extinguished, the appliance will not continue releasing natural gas into the house.
  2. Combustion gases are exhausted outdoors through an exhaust flue. The gas is burned in a sealed chamber that is vented to the outdoors -- the air or water being heated passes through a heat exchanger in the combustion chamber.

Even with these two systems in place, CO detectors are still required, and odors are added to natural gas to make leaks detectable.

By contrast, a natural gas-burning stove or oven has neither of these safety measures (some newer models may have flame sensors*, but most existing ones don't). If the flame goes out the gas keeps coming, and the combustion gases are released directly into the living space. An exhaust hood will remove the combustion gases, but also most of the heat.

If you are using the oven/stove as intended, you are likely in the kitchen where you will be able to smell the natural gas, or see that that flame is yellow and/or smoking, an indication of the incomplete combustion that can generate CO. You will also not be using the appliance for several hours every day (or if you are, you are likely using an exhaust hood).

*In the U.S. and Canada, CSA/ANSI Z21.1-2018/CSA 1.1-2018 is the standard for "household cooking gas appliances". If someone has institutional access they could check if flame sensors are required, but this would be a recent change.

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    Note that some gas stoves (in fact all that I have personally seen and used in Europe) do have a flame sensor working exactly as you described. The combustion gases are still in the kitchen though, so that points is still valid. – quarague Feb 18 at 8:37
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    Point 2 is the relevant one with regard to CO levels. Point 1 mostly makes it harder to accidentially blow the building up (and is also available in all stoves I have seen so far, except perhaps some camping equipment). – Hulk Feb 18 at 9:00
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    @quarague I'm in Europe too, but there are plenty of older gas stoves/ovens around here that don't have them. If I recall correctly they only became mandatory on new equipment sometime in the 1990's. My stove and oven don't have them and they are from 1984. Will finally be replaced this summer when I remodel the kitchen. – Tonny Feb 18 at 12:44
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    I'm pretty sure that all gas ovens sold in the last 40 years in the US have included mechanisms to limit the amount of gas released if the flame goes out, even though stovetops generally don't. I think the rationale is that ovens are commonly used to bake things for long periods of time and are consequently expected to be left unattended while in use, but stoves are not. I don't know if they would completely shut off gas, but they would at most operate a small pilot light and then only feed gas to the main burner while the pilot light is lit. – supercat Feb 18 at 18:48
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    This seems like the CDC is greatly overexagerating the actual risks, assuming you aren't leaving the thing running overnight or walking away for hours on end. I don't know of any cooks who monitor their stove all day when making stock or a stew, because I can count on zero hands the number of times the gas has gone out on a modern stove. But the problem with this approach is that it pretends their are no risks associated with being in a literally freezing house for days on end. People aren't doing this out of mild discomfort, and thus a relative risk approach must be undertaken. – eps Feb 19 at 1:47
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According Non-Fire Carbon Monoxide Deaths Associated with the Use of Consumer Products 2003 and 2004 Annual Estimates by the U.S. Consumer Product Safety Commission:

In the US, deaths due to CO from "Gas Ranges/Ovens" were:

1999: 6
2000: 12
2001: 9
2002: 3
2003: 3
2004: 4

According to Carbon Monoxide Poisoning: Gas-fired Kitchen Ranges:

51 percent of kitchen ranges tested raised CO concentrations in the room above the EPA standard of 9 parts per million. Five percent had carbon monoxide levels above 200 parts per million

Also, death can occur due to using up too much of the oxygen in the combustion, as explained in Mother and 2 Infants Found Dead, and Use of Stove for Heating Is Implicated New York Times 10 January 1998.

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    Deaths are only part of the issue. There are reports of more than 300 cases of CO health issues in Texas during the recent weather events (and a few CO related deaths as well) – alephzero Feb 18 at 14:50
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    MMWR has some confirmed cases of death, but from using gas burners (or even charcoal grills) inside tents cdc.gov/mmwr/preview/mmwrhtml/mm4832a1.htm @alephzero: CO poisoning can result from appliances intended for heating alas, as this older MMWR report details: cdc.gov/mmwr/preview/mmwrhtml/00039315.htm – Fizz Feb 18 at 21:57
  • And on note with hypoxia (lack of oxygen), your body does NOT detect lack of oxygen, but a build-up of carbon dioxide (CO2). The gas stove using up too much oxygen, and then creating CO (which your body does NOT detect that well), you will simply get sleepy, go to sleep, and die. – Nelson Feb 20 at 8:53
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While it looks simple to the naked eye, combustion is a ridiculous chemical mess:

A detailed kinetic model of propane ignition and combustion in air is developed. The model includes 599 reactions with 92 species and invol ves both the high-temperatureand low-temperature mechanisms of oxidation.

This is expected as combustion of a hydrocarbon molecule does not occur instantly. When say, a propane molecule (C3H8) bumps into an O2 molecule, if they're not hot enough (ie, fast enough) to provide the activation energy required to initiate the reaction they will just bounce off each other and nothing happens. If the activation energy is available however, either from the molecules themselves or with the help of a bystander like a free radical or a catalyst, then the reaction starts. What happens depend on how the molecules collide, which means there are many possible combinations, and every step from "C3H8 + nO2" to "CO2 + H2O" is its own reaction with its own kinetics.

enter image description here

So you may ask "what is HO2 isn't is supposed to be H2O", well when molecules get whacked inside a flame with lots of free radicals in the vicinity they will rearrange in all sorts of ways, leading to intermediary products that are more or less stable (HO2 would be of the "less stable" variety since it's a free radical) which then react with whatever they can find, towards the final products of the reaction.

From the point of view of breathing humans, problems occur when the flame lacks enough oxygen to allow all the intermediary products to combust into CO2 and H2O. But this can also occur if the flame hits a cold object, like the bottom of a kitchen pot. This robs the gas molecules of their energy and prevents many reactions from occuring. The most unstable products will still react and end up decomposed into CO2 and H2O, but more stable molecules like CO will not react further with oxygen if the temperature is too cold.

I've dug up this old paper which contains lots of useful measurements.

Summary: burning gas in air generates a lot of carbon monoxide (CO) which then, under normal conditions, also reacts with oxygen and burns, producing CO2. However:

  • When the flame is yellow, combustion is incomplete due to lack of oxygen, which produces a lot of CO.

  • When the flame is blue but licks the bottom of the pot, it is cooled before combustion is complete, again producing high amounts of CO.

  • They find very little CO from an open blue flame in air, or when the bottom of the pot is far enough to not cool the flame before combustion has completed.

In a gas oven, you usually don't see the flame, so there is no way to visually check for this. Besides, the flame will be running against the sheet metal at the bottom of the oven, so it could be cooled by contact with the metal and produce lots of CO. In fact an oven combines both ways to produce CO: insufficient airflow due to dust plugging the vents, and flame being cooled on contact with metal. So I'd say chemistry agrees with CDC advice. There is definitely a risk of CO poisoning.

According to these papers, using a gas range for heating would probably not generate enough CO to cause problems, but it still is a very bad idea to use that as heating for many other reasons that have nothing to do with CO. If this is an emergency situation in the winter, people will probably plug up the ventilation and turn the room into an airtight container in an attempt to stay warm, which means excess CO2 or oxygen depletion are possible.

Also, as the second paper mentions, if you do a really good job of making the room airtight, when enough oxygen is consumed and concentration drops below about 15%, which is still breathable, combustion will stop and gas will be released into the room directly. That would displace the air and people would asphyxiate. Explosion would only occur when enough oxygen is brought back in, for example by opening the door while trying to get out. But it could also occur if, for example, the oven flame goes out first due to lack of oxygen, and there is no flame detector to turn off the gas, and the burners on the top of the stove are still burning due to having access to more oxygen.

Excess CO2 will also kill you, of course, but unless you're fast asleep you will feel it coming.

Besides, burning gas releases water vapour in the air, which will condense on the walls and ruin them, cause mold to grow, etc.

So, even if the advice is technically somewhat wrong about blaming only CO, it's still good advice. If fear of carbon monoxide prevents people from succumbing to good old asphyxiation and/or explosion, in a blackout situation where 911 isn't answering the calls, that's good enough.

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    The "According to these papers" paragraph and what follows, +1. It's probably fine, presuming you aren't in a cumulative situation where heating your house with a stove has become necessary. – Mazura Feb 21 at 2:57
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The CDC and the EPA are generally correct. However, they say "never."

In a place that is not sealed against external air or has adequate ventilation, you can use an unvented gas heater. There are camping heaters for this purpose.

When I was a graduate student and for some time afterwards, I lived in a drafty old house that was heated with old gas space heaters. Because there was outside air coming in they were fairly safe. I had no need to use the gas stove for heat because whatever heat these primitive units produced eventually made its way to the kitchen and was vented up into the attic.

In a later house, we sometimes used the gas stove for heat, because it didn't have any other heat. This was in Texas. The house had 4 bedrooms, 3 poorly sealed outside doors, and one could feel cold outside air coming in around the windows and through the electrical outlets. Otherwise, what it needed, except a few days a year, was cooling, not heating. A girlfriend ruined the gas oven by turning it on for heat and leaving the door open, which of course blew the thermostat.

I don't intend to contradict any of the other answers, which are correct, only to suggest that not every rule, even from the CDC and the EPA, applies 100% of the time.

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    All in all, this answer seems to come down to an anecdote of "I've done X several times and survived", which does not answer how dangerous X is. – Hulk Feb 18 at 16:32
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    The product you linked says not to use indoors or in sealed spaces. – Joe W Feb 18 at 20:22
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    "Especially as CO and CO2 may accumulate near the floor of the room ..." - Why would CO accumulate near the floor of the room? It's very slightly lighter than air, but the difference is so small that it distributes itself evenly. – marcelm Feb 19 at 11:11
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    @Joe W It would be fine for the typical "tumbledown shack in Bigfoot county." These guidelines, like the ones from the CDC and EPA, are stated as absolutes but in reality apply only to the modern more-or-less hermetically "sealed" houses and apartments. And also offices, where you can't even crack a window. – Wastrel Feb 19 at 13:41
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    Welcome to the site. Answers here must be based in scientific analysis, properly sourced, and cited if necessary. Personal experience is not what is sought here. Now, the existence of the gas space heaters is a good start, imo, and "use with enough ventilation" seems obvious to me, but that doesn't satisfy the site rules. You'd need to follow with evidence regarding that ventilation, but will probably be tough since those items are explicitly for outdoor use. You'll have to edit this answer to prevent it's deletion. – fredsbend♦ Feb 19 at 15:04
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Gas ranges are dangerous even for cooking!

(Other risks like fire, explosion or CO poisoning are also easilly found to be higher from numerous sources.)

Gas heaters for use without dedicated ventilation do exist, but they have flame-out protection, low oxygen protection, topple protection and are built with less attentive use in mind. Most of them are catalytic, meaning no free flame and low CO as well.

On the other hand, the only safety feature in a gas stove I have ever seen is a flame-out protection. Good, but not enough to sleep around it.

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    Welcome to Skeptics.SE. Google searches are not a substitute for reliable sources for answers, they're generally fodder for more questions, and it does not address the question. Stay focused on the question, not a general discussion of gas vs electric, and away from tangents. – Schwern Feb 18 at 20:50

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