# Carbon Monoxide **URL:** \ **Category:** Factual Questions\ **Created:** [June 26, 2016, 8:48pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443 "2016-06-26T20:48:31Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Gbro](https://avatars.discourse-cdn.com/v4/letter/g/c6cbf5/32.png) [@Gbro](https://boards.straightdope.com/u/Gbro)\ **Post date:** [June 26, 2016, 8:48pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/1 "2016-06-26T20:48:31Z")
Question came up; Does the catalytic converter on a gasoline automobile remove carbon monoxide to where it may be safe/safer to be in a confined space (garage with door closed) with engine running??? ---
**Author:** ![Great\_Antibob](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@Great\_Antibob](https://boards.straightdope.com/u/Great_Antibob)\ **Post date:** [June 26, 2016, 8:52pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/2 "2016-06-26T20:52:57Z")
Absolutely not! Yes, it will be ‘safer’ but still not safe by any stretch of the imagination. Please do not try this. It’s a good way to die. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [June 26, 2016, 8:54pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/3 "2016-06-26T20:54:45Z")
Not safe, safer in some small degree. It’s really not safe but your exposure to CO would be far less than it was before the days of catalytic converters and other pollution control and efficiency improvements in car engines. There have been claims that people trying to commit suicide or accidentally staying in a garage with a car running have not been dying as rapidly, or as thoroughly as once before. The result is brain damage instead of death. ---
**Author:** ![Procrustus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/procrustus/32/2994_2.png) [@Procrustus](https://boards.straightdope.com/u/Procrustus)\ **Post date:** [June 26, 2016, 8:55pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/4 "2016-06-26T20:55:24Z")
No. Modern Cars produce less CO than in the past, but not safe enough to run in a confined space. [Not worth taking any chances.](http://www.abe.iastate.edu/extension-and-outreach/carbon-monoxide-poisoning-vehicles-aen-208/) > [@](#): > > How does the catalytic converter reduce the risks of CO poisoning? The typical catalytic converter found on most newer cars and trucks combines oxygen with carbon monoxide to form non-poisonous carbon dioxide (CO2) reducing the high concentrations in the exhaust manifold (typically 30,000 ppm or more) to low concentrations (typically below 1,000 ppm after the catalytic converter). Tailpipe concentrations of carbon monoxide in gasoline engines without catalytic converters are typically from 30,000 to over 100,000 ppm, depending on the condition of the engine. > > How can CO poisoning occur if the engine has a catalytic converter? Exhaust gas that leaks out before the catalytic converter has high CO concentrations. Out-of-tune or misfiring engines produce elevated concentrations of carbon monoxide and unburned fuel that can destroy the catalytic converter. During cold starts the catalytic converter is ineffective. And if there is insufficient oxygen (caused by operation in a closed building or with a defective oxygen system), there will not be enough oxygen for oxidizing the CO to CO2. ---
**Author:** ![Gbro](https://avatars.discourse-cdn.com/v4/letter/g/c6cbf5/32.png) [@Gbro](https://boards.straightdope.com/u/Gbro)\ **Post date:** [June 26, 2016, 11:43pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/5 "2016-06-26T23:43:18Z")
Thanks all for the supportive replies. This question came in when an emergency care worker overheard another telling a pt. that was found in a running car inside a building that a car with a catalytic converter will not produce enough Co to be lethal. My thinking is a cold engine will produce much more Co than a hot engine running at hwy speeds, but that is just a WAG. The person was removed from the exposure very early and a 72 hour hold was initiated by LEO. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 27, 2016, 12:55pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/6 "2016-06-27T12:55:51Z")
> [@Gbro](#): > > My thinking is a cold engine will produce much more Co than a hot engine running at hwy speeds, but that is just a WAG. A cold-start will indeed produce most of the emissions associated with a short trip, for a couple of reasons: #1: cold-start enrichment. When the engine is cold, fuel doesn’t vaporize well, so the ECU injects extra fuel to ensure the formation of a combustible mixture. This means some unburned hydrocarbons and CO are carried out of the engine with the exhaust gas. #2: cold cat. The catalytic converter doesn’t become active until it warms up, so the extra-dirty exhaust of a cold-start actually does make it all the way out to the environment. Assuming: -A warmed-up engine at idle -with a properly functioning emissions control system -in a late-model car the exhaust will have very low CO concentration, on the order of a few hundred ppm. [while this is usually not enough to kill a healthy adult,](https://en.wikipedia.org/wiki/Carbon_monoxide_poisoning#Signs_and_symptoms) it can make you pretty damn sick. If any of the above assumptions are not true, then exhaust CO concentration is likely to be _much_ higher. IOW, no, it is generally regarded as not safe to run a car in an enclosed space. Note also that portable generators don’t have the same emissions control systems that cars do, so they put out a LOT more CO/NOx/UHCs. Whenever there’s a prolonged power outage, you inevitably see a news report where someone fired up a generator in the garage or basement and killed their whole family with CO poisoning. ☹ ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [June 27, 2016, 4:31pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/7 "2016-06-27T16:31:49Z")
Part of our house is over the garage. One time **Mrs. FtG** left the car running in the garage for a bit to go back and get something. Our CO alarm went from 0 to some low, single digit number. Not enough to set off the alarm, but alarming nonetheless. (This was with the her car’s garage door open!) We try to avoid that now. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [June 29, 2016, 11:46am UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/8 "2016-06-29T11:46:21Z")
What will happen is that O2 decreases in the air, the incorrect burning will occur, and the CO is produced. Anyway the engine is turned to run when driving and at idle it may run very poorly and ungreen. especially its not keeping the Cat convertor hot enough to work ? ---
**Author:** ![elbows](https://avatars.discourse-cdn.com/v4/letter/e/b3f665/32.png) [@elbows](https://boards.straightdope.com/u/elbows)\ **Post date:** [June 29, 2016, 12:04pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/9 "2016-06-29T12:04:18Z")
Pt=??? Part time? Physical therapist? ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [June 29, 2016, 12:11pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/10 "2016-06-29T12:11:34Z")
Platinum. ---
**Author:** ![svd678](https://avatars.discourse-cdn.com/v4/letter/s/53a042/32.png) [@svd678](https://boards.straightdope.com/u/svd678)\ **Post date:** [June 29, 2016, 12:15pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/11 "2016-06-29T12:15:37Z")
patient ---
**Author:** ![jtur88](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jtur88](https://boards.straightdope.com/u/jtur88)\ **Post date:** [June 29, 2016, 12:33pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/12 "2016-06-29T12:33:08Z")
> [@Great\_Antibob](#): > > Please do not try this. It’s a good way to die. Sadly, no it isn’t. It used to be, but now it is just a good way to turn yourself into a brain-damaged babbling idiot. CO suicides in garages are now rarely successful, for this reason. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [June 29, 2016, 12:36pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/13 "2016-06-29T12:36:28Z")
If I may … a garage full of CO[sub]2[/sub] is also very unhealthy … ---
**Author:** ![Atamasama](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/atamasama/32/12961_2.png) [@Atamasama](https://boards.straightdope.com/u/Atamasama)\ **Post date:** [June 29, 2016, 4:16pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/14 "2016-06-29T16:16:20Z")
Cue jokes about suicide in a garage with a Tesla… ---
**Author:** ![boffking](https://avatars.discourse-cdn.com/v4/letter/b/858c86/32.png) [@boffking](https://boards.straightdope.com/u/boffking)\ **Post date:** [June 29, 2016, 5:16pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/15 "2016-06-29T17:16:58Z")
> [@elbows](#): > > Pt=??? > > Part time? > > Physical therapist? Point ---
**Author:** ![USCDiver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/uscdiver/32/354_2.png) [@USCDiver](https://boards.straightdope.com/u/USCDiver)\ **Post date:** [June 29, 2016, 5:19pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/16 "2016-06-29T17:19:53Z")
I’ve seen cases of elderly folks in little townhomes dying after forgetting to turn their car off and closing their one car garage door. They weren’t even in the garage, but there was enough CO in the house to cause problems. ---
**Author:** ![zwede](https://avatars.discourse-cdn.com/v4/letter/z/ac91a4/32.png) [@zwede](https://boards.straightdope.com/u/zwede)\ **Post date:** [June 29, 2016, 5:30pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/17 "2016-06-29T17:30:59Z")
So now I’m curious: What happens to the CO once it’s out in the air? It has to become something less toxic (CO2?) pretty quickly. If not anyone next to a busy road would die. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 29, 2016, 5:31pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/18 "2016-06-29T17:31:48Z")
> [@watchwolf49](#): > > If I may … a garage full of CO[sub]2[/sub] is also very unhealthy … The difference is that a high concentration of CO2 produces very unpleasant sensations and compels you to seek fresh air; try holding your breath for a while and you’ll feel what I mean. This is why suicide-by-plastic-bag-over-head generally also requires a strong sedative i.e. to ensure that the victim does not try to remove the bag. Low CO concentrations may give you a headache before they render you insensate, but they won’t cause the same panicky “gotta get fresh air” compulsion as CO2. A high concentration of CO will quickly render you unconscious, no time for a headache. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [June 29, 2016, 5:40pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/19 "2016-06-29T17:40:23Z")
> [@zwede](#): > > So now I’m curious: What happens to the CO once it’s out in the air? It has to become something less toxic (CO2?) pretty quickly. If not anyone next to a busy road would die. The good news: It takes an atom from 02 to form CO2. The bad news is the spare O joins with O2 to form O3: ozone. CO is a significant cause of ozone pollution in urban areas. ---
**Author:** ![zwede](https://avatars.discourse-cdn.com/v4/letter/z/ac91a4/32.png) [@zwede](https://boards.straightdope.com/u/zwede)\ **Post date:** [June 29, 2016, 5:46pm UTC](https://boards.straightdope.com/t/carbon-monoxide/758443/20 "2016-06-29T17:46:03Z")
> [@ftg](#): > > The good news: It takes an atom from 02 to form CO2. The bad news is the spare O joins with O2 to form O3: ozone. CO is a significant cause of ozone pollution in urban areas. So what is the issue in a closed garage? The reaction is not quick enough allowing too much CO to build up? Or does the reaction require sunlight? [Next page](https://boards.straightdope.com/t/carbon-monoxide/758443.md?page=2)