If CO isn't a greenhouse gas why don't we ban catalytic converters?

December 4, 2018 11:53 AM

If catalytic converters convert CO to CO2 and CO isn't a greenhouse gas then is releasing CO actually the lesser of two evils? I know very little about why CO is so bad other than the suffocating in closed spaces without knowing it bit so explain it to me nicely :)
posted by zeoslap to Science & Nature (14 answers total)

Catalytic converters covert the Carbon Monoxide and unburned hydrocarbons into carbon dioxide and water (CO + HC -> CO₂ + H₂O). They also remove various nitrous oxides (NO_x).

While CO is definitely bad for your health (since your body will use it rather than oxygen if it can), but I believe it's more the unburned hydrocarbons and nitrous oxides that are the main reasons for the catalytic converters.
posted by sideshow at 12:17 PM on December 4, 2018

I think suffocating in enclosed spaces is enough... It does that because it binds in our bodies like oxygen, and needed oxygen can't get transported.

It is the leading cause in poisoning in the US already already according to newyork. Gov
posted by AlexiaSky at 12:19 PM on December 4, 2018

The short answer is that it's not the lesser of two evils; carbon monoxide is considerably nastier, and at lower concentrations, than carbon dioxide. CO2 is also easier to get rid of on a global scale, because plants can't breathe CO.
posted by tchemgrrl at 12:21 PM on December 4, 2018 [3 favorites]

It is difficult to kill yourself by sitting in a running car, in an enclosed space. This did not used to be the case. Protection from CO is an important goal.
posted by Midnight Skulker at 12:22 PM on December 4, 2018

Response by poster: How is CO2 easier to get rid of on a global scale? Isn't it the primary contributor to climate change? Is that really less important than the avoidable suffocation issue (I mean we could have mandatory CO alarms inside enclosed spaces right? That seems solvable)
posted by zeoslap at 12:26 PM on December 4, 2018

Response by poster: Also three way catalytic converters get rid of CO, NO, and NO2 but you could make a two way that would still remove NO and NO2 but leave the CO as is.

Not arguing, I'm clearly wrong, but just trying to understand.
posted by zeoslap at 12:29 PM on December 4, 2018

Best answer: In the atmosphere, CO oxidizes to CO2 (and ozone) on a one-to-two-month timescale. You're not going to be able to sink carbon in the form of atmospheric CO in any lasting way.
posted by lozierj at 12:31 PM on December 4, 2018 [11 favorites]

Response by poster: @lozierj - rats, thought I had this whole global warming thing solved. Sigh. Makes perfect sense, thanks.
posted by zeoslap at 12:37 PM on December 4, 2018

>How is CO2 easier to get rid of on a global scale?
Plant plants.

Releasing CO outside doesn't magically make it less toxic, it just makes it more inescapable. Part of the huge reduction in smog in the US has been due to the use of catalytic converters. You can look up things like the LD50 for CO vs. CO2, and the side effects of CO and CO2 as pollutants. I suppose that if you decreased the human lifespan, that is an indirect way of reducing the rate of climate change....
posted by tchemgrrl at 12:39 PM on December 4, 2018 [3 favorites]

There is a trade off. C02 might kill you in the next, say, 30 years. CO will kill you in 5 minutes. Which would you rather have? It isn't just CO in your garage that is bad. Just low level ambient CO near roads and highways affects the health of you and your kids today, not 30 years from now.

You find the same trade off between gasoline and diesel cars. Diesel cars produce less CO2 per mile but more NO and particulates per mile. So, at least in the U.S., gasoline cars are preferred because the extra CO2 might kill you in 30 years, but the NO and particulates affect your health adversely today.
posted by JackFlash at 2:43 PM on December 4, 2018

Catalytic converters don't just convert CO to CO2. They also remove hydrocarbons. Smog kills people. Wikipedia points a study that says vehicle air pollution causes 53,000 early deaths per year in the United States and that's with catalytic converters. Without converters that number would zoom up.
posted by rdr at 5:11 PM on December 4, 2018

One of the arguments for diesel cars was that diesels produce less CO2. They do. But they also produce a lot of nitrogen oxide, which is not good for humans at short range and is harder to neutralize than CO. So, when Volkswagen came along and said they could and did build a diesel car with low NO emissions, the European regulators were excited. This would make diesels a slam-dunk over gas cars: less CO2 emitted than gasoline, clean NO emissions.

Turns out they couldn't, so they cheated instead. But this exact problem- trading lower CO2 emissions for higher shortrange nasties- is part of the diesel/gasoline dynamic.
posted by BungaDunga at 6:00 PM on December 4, 2018

And on top of all that, burning gasoline produces a metric shit ton of CO2 by itself. Getting rid of the catalytic converters to save on CO2 emissions isn’t too far off from ordering a large pizza and getting a diet coke to save on calories.
posted by hwyengr at 6:45 PM on December 4, 2018 [1 favorite]

Please be aware that you do NOT need to be in an enclosed space. This is a very dangerous misconception.

Carbon monoxide sickens and sometimes kills people in the great outdoors. Lake Havasu in Arizona is one place known for this, but boaters elsewhere can succumb even without "teak surfing." So too with snow mobile users or anyone near a generator or running engine for too long on a still day.

And since it will eventually oxidize, you get the CO2 anyway, after a stage as one of the nastiest, sneakiest poisons known. Carbon monoxide is intensely evil.
posted by wjm at 2:15 AM on December 5, 2018 [1 favorite]