A Groundbreaking New Study Foils The Elevated-CO2-Is-Toxic-To-Humans Narrative

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Over the years there has been a sustained effort to portray human exposure to very high levels of CO2 as toxic.  A new study undercuts these claims, as the decision-making performances of controlled-experiment participants were not impaired when exposed to CO2 concentrations as high as 15,000 ppm. 

As a political activist, Al Gore has often referred to CO2 as a pollutant, even going so far as to characterize anthropogenic CO2 emissions as “global warming pollution.

To that end, a study has just been published that suggests exposure to very high CO2 levels (1,500 ppm and 2,500 ppm) impaired the judgment and decision-making of airplane pilots (Allen et al., 2018), a result that reinforces the characterization of CO2 as a toxic gas.

And yet in another new study (Rodeheffer et al., 2018) it was determined that exposing submarine sailors to CO2 levels that reached 15,000 ppm did not impair their decision-making or overall cognitive functioning compared to sailors exposed to 600 ppm or 2,500 ppm.

In fact, sailors exposed to 15,000 ppm CO2 concentrations had better decision-making scores than sailors exposed to 2,500 ppm on 7 of the 9 measurement categories.

These findings undermine or at least cast doubt on claims that exposure to very high CO2 concentrations have a significant effect on human judgment or decision-making, which may assist in foiling efforts to portray CO2 as a toxin or pollutant.


Rodeheffer et al., 2018

Acute Exposure to Low-to-Moderate Carbon Dioxide
Levels and Submariner Decision Making

BACKGROUND: Submarines routinely operate with higher levels of ambient carbon dioxide (CO2) (i.e., 2000 – 5000 ppm) than what is typically considered normal (i.e., 400 – 600 ppm). Although significant cognitive impairments are rarely reported at these elevated CO2 levels, recent studies using the Strategic Management Simulation (SMS) test have found impairments in decision-making performance during acute CO2 exposure at levels as low as 1000 ppm. This is a potential concern for submarine operations, as personnel regularly make mission-critical decisions that affect the safety and efficiency of the vessel and its crew while exposed to similar levels of CO2. The objective of this study was to determine if submariner decision-making performance is impacted by acute exposure to levels of CO2 routinely present in the submarine atmosphere during sea patrols.

METHODS: Using a subject-blinded balanced design, 36 submarine-qualified sailors were randomly assigned to receive 1 of 3 CO2 exposure conditions (600, 2500, or 15,000 ppm). After a 45-min atmospheric acclimation period, participants completed an 80-min computer-administered SMS test as a measure of decision making.

RESULTS: There were no significant differences for any of the nine SMS measures of decision making between the CO2 exposure conditions.

DISCUSSION: In contrast to recent research demonstrating cognitive deficits on the SMS test in students and professional-grade office workers, we were unable to replicate this effect in a submariner population—even with acute CO2 exposures more than an order of magnitude greater than those used in previous studies that demonstrated such effects.

Graph Source: Rodeheffer et al., 2018
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48 responses to “A Groundbreaking New Study Foils The Elevated-CO2-Is-Toxic-To-Humans Narrative”

  1. BobW in NC

    Understand the importance of publishing this – don’t know how it translates to the partial pressure of CO2 in the bloodstream (pCO2). As CO2 builds up in the blood, as the pCO2 rises, a person will breathe more rapidly to blow off the excess – that’s normal physiology. However, when the pCO2 exceeds 40 ppm, it becomes extremely toxic and actually depresses respiration, typically resulting in death. How all that translates to the 15,000 ppm that sailors breathe, I don’t know. But, yes, CO2 can produce toxicity under certain conditions.

    1. Hivemind

      Surely not 40 ppm? We are already at 400 ppm.

      1. BobW in NC

        Just to be. Clear in what I said: the 40 ppm is the partial pressure (pCO2) in someone’s bloodstream, not the atmosphere.

        1. Yonason
  2. SebastianH

    I am sure the navy’s of this planet will soon get rid of their CO2 scrubbers, also every space agency. Finally, Kenneth shows us that we can happily breathe CO2 with no limit (15000 ppm) 😉

    1. spike55

      “Finally, Kenneth shows us that we can happily breathe CO2 with no limit “

      That’s a particularly moronic statement, even from you seb.

      Not K, it was the study that shows that high levels of CO2 didn’t have any influence on cognitive.

      Emotions were not studied, so where did you get the “happily” from?

      There was a limit on the CO2 concentration, 15000, so why say ” no-limit”?

      You are just making crap up, as always.

      The study was REAL MEASURED SCIENCE.. seb. !!

      Something which is a total enema to you.

      You could prove me wrong and produce some empirical measurements of CO2 warming.

      But you won’t will you.. because you CAN’T

      1. SebastianH

        Not K, it was the study that shows that high levels of CO2 didn’t have any influence on cognitive.

        Kenneth isn’t just quoting a study, he has stuff to say about it … maybe you should learn to read. Especially after this “analysis” of what I wrote 😉

        As always, the “skeptic” in you want to be the clown in this community. An interesting strategy.

        1. spike55

          ZERO-EVIDENCE seb yaps mindlessly YET AGAIN.

          You have ZERO to counter anything the study said, OR anything K said.

          You are empty AS ALWAYS.

          REAL MEASURED SCIENCE.. something that is an anathema to you. !

          1. SebastianH

            You have ZERO to counter anything the study said, OR anything K said.

            Kenneth’s claim:
            “These findings undermine or at least cast doubt on claims that exposure to very high CO2 concentrations have a significant effect on human judgment or decision-making, which may assist in foiling efforts to portray CO2 as a toxin or pollutant.”

            My reply:
            “I am sure the navy’s of this planet will soon get rid of their CO2 scrubbers, also every space agency. Finally, Kenneth shows us that we can happily breathe CO2 with no limit (15000 ppm) :-)”

            If you fail to see how this counters his claim, well … do you at least recognize that it’s sarcasm?

          2. spike55

            Nothing you say counters K’s claims.. EVER. !!

        2. spike55

          “Kenneth isn’t just quoting a study”

          WOW, you really have comprehension ISSUES don’t you.

          You MUST be pretending.. no-one is as dumb as you are pretending to be.

    2. spike55

      You do know there is a limit to how much H2O we can breathe, don’t you seb..

      Does that make H2O “toxic” ?

    3. Bitter&twisted

      I would like to see our troll breathe a CO2-free atmosphere for a few hours…

      1. SebastianH

        Do you think you need CO2 in the atmosphere to be able to breathe?

        1. spike55

          The lung’s air/blood interface requires a certain level of CO2 on both sides.

          Fortunately, the human body manufactures that CO2 from the carbohydrates it has consumed.

          And GUESS where those carbohydrates come from, seb.

    4. sunsettommy

      Sebastian didn’t read the paper at all:

      Rodeheffer et al., 2018

      “BACKGROUND: Submarines routinely operate with higher levels of ambient carbon dioxide (CO2) (i.e., 2000 – 5000 ppm) than what is typically considered normal (i.e., 400 – 600 ppm). Although significant cognitive impairments are rarely reported at these elevated CO2 levels, recent studies using the Strategic Management Simulation (SMS) test have found impairments in decision-making performance during acute CO2 exposure at levels as low as 1000 ppm. This is a potential concern for submarine operations, as personnel regularly make mission-critical decisions that affect the safety and efficiency of the vessel and its crew while exposed to similar levels of CO2. The objective of this study was to determine if submariner decision-making performance is impacted by acute exposure to levels of CO2 routinely present in the submarine atmosphere during sea patrols.

      METHODS: Using a subject-blinded balanced design, 36 submarine-qualified sailors were randomly assigned to receive 1 of 3 CO2 exposure conditions (600, 2500, or 15,000 ppm). After a 45-min atmospheric acclimation period, participants completed an 80-min computer-administered SMS test as a measure of decision making.
      RESULTS: There were no significant differences for any of the nine SMS measures of decision making between the CO2 exposure conditions.”

      Your comment was dead before arrival, still trying to look smart but failing badly.

      1. Yonason

        @sunsettommy

        It might not be the CO2 at 1000ppm that’s the problem (most likely not, in fact).

        I remember a friend who was a navigator, and we were sitting in the mess hall. He hadn’t slept since Lincoln was in diapers (figuratively speaking). We were at ambient CO2 in the 1970s, which was almost “safe” by warmist standards. But as sleep deprived as he was, he was very functionally challenged. He picked up his toast in one hand, got butter onto his knife in the other, and spent the next 5 minutes truing to connect the butter to the bread. It was painful to watch. But it had nothing to do with CO2. It was just because he was so very very very sleep deprived. And this wasn’t any kind of combat mission. We were just going to sea trials after a yard period.

        (If SebH is true to form, he’ll say my friend wasn’t very bright. But since my friend had an MS in Math (one reason he was qualified to be a navigator), and after his discharge went on to Rutgers to get his PhD, I just wanted to head THAT slander off before it was spewed.)

        Botom line, I’d like to see what other variables were involved, BESIDES [CO2]. I mean, these are sailors were talking about here, not boy scouts. 😉

        SebhH, as usual hasn’t a clue what he’s blathering about. Of course, if he ever made sense, what would the point of him being here?

        You know, maybe if SebH took that plastic bag off of his head once in a while…

        1. SebastianH

          SebhH, as usual hasn’t a clue what he’s blathering about.

          Well, it appears to me you don’t understand what I have written above. But thanks for the nice insults again … very “true to form”.

          Is it the language barrier or do you really not get it?

          1. spike55

            And seb just blathers on with his childish attention-seeking.

            We do understand what you wrote.

            Its just ARRANT NONSENSE !

      2. SebastianH

        Sebastian didn’t read the paper at all

        That is correct. I am critizing Kenneth’s reaction to a paper like this, not the paper itself. It’s ok to not get that, sunsettommy. Maybe next time try the “you presented no counter” strategy again …

        1. spike55

          Your criticisms are totally BASELESS, MEANINGLESS and IRRELEVENT.

          You have NOTHING to back them up with.

          EMPTY as always.. poor seb.

  3. Bitter&twisted

    Exhaled CO2 is about 5% (50,000ppm) and in equilibrium with the blood.
    Don’t know where you get your 40ppm from.

    1. Yonason

      I wouldn’t want to serve in a Sub with constant extremely elevated CO2, not because it isn’t safe, but because it leaves no margin for error if the air supply fails. The currently allowable limit is 8,000 ppm, which must certainly allow for a healthy safety margin.

  4. Ric Werme

    I’m trying to understand “pCO2 exceeds 40 ppm,” which seems to be mixed units. ppm is generally used for volume or mass. Pressure is reported as Pascals (or kPa – kilopascals), or mmHG (the pressure that many millimeters deep in a mercury column). Blood pressure is reported with mmHg.

    https://www.healthline.com/health/blood-gases says:

    In general, normal values include:

    partial pressure of oxygen: 75 to 100 mm Hg
    partial pressure of carbon dioxide: 38 to 42 mm Hg

    I can’t resolve “pCO2 of 40 ppm” resolves to anything related to ppm. I suspect your measurement was really mmHg, but that doesn’t fit well either.

    Please check your source.

    1. SebastianH

      Partial pressures are usually the pressure of just one gas if it filled the entire volume. When disolved gases in liquid are looked at Henry’s law comes into play.

      Anyway, you can convert the partial pressure from a percentage and vice versa. 400 ppm of CO2 in the atmosphere is roughly 0.3 mmHg (in air).

      1. Ric Werme

        That’s not my problem – a pCO2 of 40 ppm in the bloodstream makes no sense to me whatsoever.

        The “Exhaled CO2 is about 5% (50,000ppm) and in equilibrium with the [venous] blood” does make sense. 40 ppk might make sense except for using parts per thousand.

        Also, that’s ppm by what? Neither by volume nor by mass makes sense.

        1. SebastianH

          Ric, I don’t know where those 40 ppm come from, but it’s not a problem of the unit, but more a problem of the magnitude you are having. Correct?

          Since blood transports the CO2 we exhale it makes sense that the partial pressure at that moment is around 50000 ppm as well. This converts to 37.5 mmHg … near the range you found on healthline.com

          Also, that’s ppm by what?

          Partial pressure in liquids can be expressed in ppm when you imagine the gas in the liquid being in equilibrium with the same gas in a dry sea level atmosphere. I am sure my English is not perfect enough to explain this simply, but maybe Wikipedia can help here even though skeptics don’t like Wikipedia as a source for knowledge? 😉

  5. Yonason

    RATS!

    “In a 14-day, 23 h/day, whole-body inhalation study of exposure to clean air (0.4 ppm CO, 0.1% CO2 and 20.6% O2), low-dose, mid-dose and high-dose gas mixtures (high dose of 88.4 ppm CO, 2.5% CO2 and 15.0% O2), no adverse effects on survival, body weight or histopathology were observed.”
    https://www.ncbi.nlm.nih.gov/pubmed/25600219

    No harm to the rats at 2.5% CO2.

    People aren’t rats, but biology is biology, after all, and an atmosphere of 5,000 ppm (12.5 x current 400 ppm), which is around what it was when the first complex life forms abruptly arose in the Cambrian, would probably not be a problem. Avg temps back then were allegedly 22.5 deg C, and are currently around a frigid 16 deg C.

  6. CO2isLife

    FYI, you exhale air with CO2 around 40,000 PPM. You don’t die from holding your breath for a minute or 2. Additionally, Corals also exhale air which lowers the immediate pH of the water around them, well below the general seawater pH. Mollusks have CO2 in their blood and they still make and maintain their shells. CO2 is essential for life, is much higher in your blood, and aquatic animals aren’t harmed by it at all.

    1. Yonason

      Mammalian cells are grown in phosphate/carbonate buffered culture medium with an ambient CO2 (part of the buffering system) usually of anywhere from 5%-7.5% (sometimes 4%-10%).
      https://www.ncbi.nlm.nih.gov/pubmed/5110427

      They are very healthy and happy. Elevated CO2 used in conjunction with the buffered saline growth medium does not harm the cells. It is NOT a toxin.

    2. Reziac

      About what does CO2 concentration wind up at in a rebreathing situation?

      1. spike55

        Raising CO2 in the lungs is beneficial to asthma sufferers.

        Breathing patterns that do this are used in methods such as the Buteyko method.

        CO2 is a natural bronchial dilator.

      2. Bitter&twisted

        It’s not the increased CO2 that does for you.
        It’s the lack of O2.

        1. Yonason

          Awww, ya beat me to it! 🙂

        2. spike55

          Also, a lack of CO2. A certain amount is absolutely required for the lung’s interchange action to work.

  7. Steve

    I just exhale, regardless, and in fact I can do it while I am asleep.

  8. A Groundbreaking New Study Foils The Elevated-CO2-Is-Toxic-To-Humans Narrative | Un hobby...

    […] by K. Richard, August 20, 2018 in NoTricksZone […]

  9. MattS

    I read the paper, and don’t see any reason to doubt the conclusion – we humans don’t have to worry about elevated CO2 levels in the foreseeable future. Nothing about climate here at all. I must say it looks like some just”enjoy the conflict”. To me, it’s an interesting off-topic article that warmists and sceptics don’t have to argue over.

  10. Brett Keane

    IIRC, 10percent CO2 is about the limit, 100,000ppm! Then blood acidity/carbonate problems cause a switch-off of conciousnes, leading possibly to death. I lost a friend in a barge hold that way, with bloody froth on his face.
    Different units make understanding hard, but 40,000ppm in lifesaving mouth to mouth has saved countless lives. Trolls and CAGWers should breathe deeply via nose and keep mouth closed until brain is engaged. 40,000ppm, for crying out loud.

  11. Yonason

    “I lost a friend in a barge hold that way” – Brett Keane

    Sorry to hear that.

    Are you sure it wasn’t H2S? Big problem with unvented compartments on a ship can be Hydrogen Sulfide. Just leaving a piece of fruit there to rot might be all it would take. We were told if we ever smelled rotten eggs on entering, to get out IMMEDIATELY. If you remain, you’ll soon no longer smell it, not because it’s gone, but because it deadens your sense of smell. You think you’re OK, but you aren’t.

    Hard to build up enough CO2 in a space to kill you. They never warned us about that.

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