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Science

Indoor Carbon Dioxide Levels Could Be a Health Hazard, Scientists Warn (theguardian.com) 172

An anonymous reader quotes a report from The Guardian: Indoor levels of carbon dioxide could be clouding our thinking and may even pose a wider danger to human health, researchers say. The authors of the latest study -- which reviews current evidence on the issue -- say there is a growing body of research suggesting levels of CO2 that can be found in bedrooms, classrooms and offices might have harmful effects on the body, including affecting cognitive performance. "There is enough evidence to be concerned, not enough to be alarmed. But there is no time to waste," said Dr Michael Hernke, a co-author of the study from the University of Wisconsin-Madison, stressing further research was needed. Writing in the journal Nature Sustainability, Hernke and colleagues report that they considered 18 studies of the levels of CO2 humans are exposed to, as well as its health impacts on both humans and animals.

Traditionally, the team say, it had been thought that CO2 levels would need to reach a very high concentration of at least 5,000 parts per million (ppm) before they would affect human health. But a growing body of research suggests CO2 levels as low as 1,000ppm could cause health problems, even if exposure only lasts for a few hours. The team say crowded or poorly ventilated classrooms, office environments and bedrooms have all been found to have levels of CO2 that exceed 1,000ppm, and are spaces that people often remain in for many hours at a time. Air-conditioned trains and planes have also been found to exceed 1,000ppm.

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Indoor Carbon Dioxide Levels Could Be a Health Hazard, Scientists Warn

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  • by Anonymous Coward on Monday July 08, 2019 @10:36PM (#58894204)

    You can get them for about $80. It changed my life: I now properly ventilate my apartment and workplace, and am much more productive.

    • You can't properly ventilate your apartment and workplace without a CO2 measuring device?
    • 483 PPM according to the monitor on the wall of my office. Bought it during the winter, when I was worried that having the windows closed would cause CO2 to spike, and it did (routinely breaking 1600 PPM); left it up because heck, it uses almost no power and it's kind of neat to know.

      Once you've got an idea for the pattern - how much one person in a closed room changes the level per hour, how much difference it makes to have a door or window or whatever open, etc. - the monitor probably isn't needed any mor

  • by OrangeTide ( 124937 ) on Monday July 08, 2019 @10:41PM (#58894210) Homepage Journal

    these energy efficient homes are killing us.

    • by ShanghaiBill ( 739463 ) on Monday July 08, 2019 @11:51PM (#58894298)

      these energy efficient homes are killing us.

      Solution: Heat recovery ventilation [wikipedia.org].

      • Then you still have particulate matter and chemicals to deal with. A greenhouse might be a better investment.

      • by Solandri ( 704621 ) on Tuesday July 09, 2019 @01:20AM (#58894490)
        Heat exchange can approach 100% efficiency with a counter-current heat exchanger [wikipedia.org]. The problem is humidity and to a lesser extent particulates. Particulates require filtering, which decreases the efficiency of your fans, adding additional energy load.

        Humidity is a real pain. The amount of water vapor the air can hold varies with temperature. So if the air outside is -10 C and 70% humidity, and you heat it up to 20 C to use indoors, it's no longer at 70% humidity. The humidity will drop because the air's capacity to hold water will increase as you heat it. To compensate for this, you have to add water vapor. But doing so cools the air (converting liquid water to vapor is endothermic - that's why your sweat cools you off as it evaporates). So even if your heat exchanger is 100% efficient, you still have to add energy to the incoming air to keep it at the same temperature as the outgoing air.

        Air conditioning runs into a similar problem. As you cool the air, the humidity increases. You take 35 C air outside and cool it to 20 C, and your inside air reaches 100% humidity. To correct for this, air conditioners over-cool. They'll cool the air to (say) 10 C. The humidity hits 100% and excess water vapor condenses and drops out the air (why water drips out of your air conditioner). Then the air is warmed back up to 20 C dropping its humidity below 100%. Since the process is the reverse of evaporation above, it's exothermic. But the energy you gain goes into the water (or rather, whatever the water condenses onto - that's why your chilled beer warms up as water condenses on the bottle), not the air. So you still have to heat up the air from 10 C to 20 C.

        One of the solutions in Asian homes (where people are typically barefoot, and sit on the floor) is in-floor heating and cooling. You don't bother trying to heat/cool the air. Instead, you heat/cool the floor. This sets up a direct temperature exchange between the floor and your body for comfort, while minimizing the complications of regulating the humidity in the air.
        • by Rei ( 128717 )

          Even when the goal is to heat / cool the air, in-floor is more efficient, particularly when you have high ceilings.

          Imagine that you have a convention centre, and a bunch of people you're trying to keep cool (~20C) in a hot climate (~35C), all giving off heat. If you have your AC vents at the ceiling, you end up with an inverted stratification where there's consistently warm air near the people at the ground (who are emitting said heat) and cold air near the ceiling that has to diffuse / convect down. You ha

          • by Anonymous Coward
            Wrong. Cool air does not rise, especially if there's hotter air above it. In your scenario, the cool air will be trapped at people's feet. The proper way is to vent cool air at the ceiling and draw from the floor. The cool air will naturally fall (which can be augmented by ceiling fans), using convection to advantage rather than fighting against it.
            • by jbengt ( 874751 )
              If you have A/C supply and return both at the ceiling, you definitely can have stratification where it is hotter at the floor, especially if you have high ceilings. However it is not that hard to design such a system to overcome stratification when cooling; when heating with air more than 10F to 15F above room temperature, stratification will be an issue.
              There is a definite advantage, if properly designed, to supplying the cool air at the floor and returning/exhausting it from the ceiling, especially for
            • by Rei ( 128717 )

              To repeat:

              you end up with an inverted stratification

              The "hot air rising, cold air sinking" is an ideal stratification, which will occur A) in the absence of significant diffusion, and B) given sufficient mixing time - two constraints that are far from universally guaranteed (and if they're guaranteed, would apply to both floor-entry and ceiling-entry systems). Key to preventing this is that the fact that if your AC inlets are on the ceiling, then this is the guaranteed coldest place in the room. Air is n

          • Cooling a room from the floor gives the best efficiency for removing a given amount of heat with an air conditioner, sure. But it neglects the central objective of maintaining a comfortable environment in the room. Yer gonna freeze folks' toes off, Rei.
        • The humidity issue can be overcome by using a thermal wheel [wikipedia.org] instead of a counter-current heat exchanger. These are typically called "energy recovery ventilators" where counter-current heat exchangers are called heat recovery ventilators .
        • by ceoyoyo ( 59147 )

          It seems like a more sophisticated heat exchanger could deal with that issue. When the water vapour from the warm air condenses in the heat exchanger, it could be recovered and used to humidify the incoming air. Vice versa for AC.

    • by AmiMoJo ( 196126 )

      TFS says that air conditioning causes it too.

    • by hackertourist ( 2202674 ) on Tuesday July 09, 2019 @03:23AM (#58894668)

      Rubbish. Architects have to adhere to stringent regulations for everything, including ventilation capacity. Energy efficient homes are more than capable of keeping CO2 levels acceptable.

      A problem does arise when the homeowner decides not to ventilate and closes all the ventilation openings, without monitoring CO2 levels. Home ventilation suppliers responded to that by offering demand-controlled ventilation systems (using a CO2 sensor to set motor speed). Those systems may need to have their setpoints changed thanks to this research.

      • Architects maybe, builders, not so much.

        Where a through-wall vent is required (as is required for our lounge as we have a wood burner) - the "standard" offering is basically a gaping hole in the wall with a grille over it which you can paint. That's both unattractive and inefficient and leads to people blocking the grille up with tape or whatever.

        In our case, we put in a baffled vent (which cost maybe +£5 over the unbaffled version) - it's still got the same airflow volume as we're required to have, b

  • Get a window fan (Score:5, Interesting)

    by Krishnoid ( 984597 ) on Monday July 08, 2019 @11:08PM (#58894254) Journal

    Set up a nice cross-breeze, strike a blow against local warming, get a little fresh air.

    • With all the pollution from outside? And the open window letting in the road noise? And whatever humidity might be outside? On a hot and sunny day? AC keeps the air circulating quite nicely, I think.
    • I had these [google.com] in two houses, they were terrific.
      • by Anonymous Coward

        It'a like having a biplane in your attic!

        • by kackle ( 910159 )
          First world problems, I guess. When it's 70 degrees F at night, I can get away with running the fan for a few hours at night, sealing up the windows during the day and avoiding turning on the A/C at all, usually for several weeks. And, the fan has a (analog "dimmer") control for any speed if the noise annoys.
    • Set up a nice cross-breeze, strike a blow against local warming, get a little fresh air.

      Well, lessee.....at night, the temps aren't getting much below 80F, often staying above 80F right now...getting August weather in July. And we're likely in the 75%+ humidity at any given time now, or higher....and you think I want to shut off my AC, open a window and blow that crap air in?

      LOL...My AC pretty much cuts on mid April and doesn't shut off till about early to mid November here in the New Orleans area.

      • Well, is your AC drawing on outside air, or is it just recirculating indoor air? I've had enough of living in tropical and even subtropical climates for a while, but summers here in my temperate coastal region are getting hot enough to want AC. When it's on, though, it's basically a window fan that also cools the air while keeping the bugs out, which is all in all a very nice arrangement (though I hate that it's getting necessary).

        • Well, is your AC drawing on outside air, or is it just recirculating indoor air?

          I guess recirculating, it's a normal central AC unit that cools the whole house.

  • Go outside (Score:2, Insightful)

    by Anonymous Coward

    Go outside and play!

  • by yarbo ( 626329 ) on Monday July 08, 2019 @11:20PM (#58894268)
    The Navy has studied the effects of much higher levels and have concluded that it's not a problem. https://wattsupwiththat.com/20... [wattsupwiththat.com]
    • Did the Navy do a study about cognitive decline ?

    • by Anonymous Coward

      not a problem *for them*

    • by Anonymous Coward

      Please note: "stressing further research was needed", in other words, this is an appeal for funding. It's almost certainly complete bollocks.

    • by serviscope_minor ( 664417 ) on Tuesday July 09, 2019 @03:27AM (#58894674) Journal

      When you post a link to a source which is known to be incredibly biased, it doesn't support your point at all. And makes it look like you have an axe to grind.

    • I do like that your citation comes up with the conclusion: "I figure if the Navy thinks it is safe for men who have their finger on the nuclear weapons keys, then that is good enough for me."

      What a truly dumb approach to science.

    • The Navy doesn't want to spend money fixing the problem, but they really should, because typical office co2 levels affect human cognition [thinkprogress.org]. People are literally less intelligent in high co2 conditions.

      The military abuses enlisted severely. When you enlist you give up many supposed rights, like the right to know what the military is doing to you medically. They got my dad hooked on uppers in Korea. He was in ATC.

      • by jbengt ( 874751 )
        Consensus is that significantly above the OSHA TWA 8-hour limit of 5,000 ppm is a problem. Under 5,000 ppm there is no consensus. There have been dozens of studies, going both ways. Many earlier studies may have included confounding effects of other pollutants. There is a need for better controlled, larger studies for the lower CO2 concentrations. The study quoted in the article you linked varied ventilation for some runs and varied CO2 directly without other changes to the environment for others, and
    • I guess since the Radon scare fad has blown over people have to find something else to cause panic about so they can sell something.
  • by Anonymous Coward

    OTHER gasses / solvents / aerosols / dusts are the brain killing gorilla in the room. Brand new offgassing carpets, sheet rock, paint, cleaning products, sealants, all kinds of under-studied nasty stuff is floating around in public air in spots.
     

  • by Dan East ( 318230 ) on Monday July 08, 2019 @11:39PM (#58894296) Journal

    CO2 is what your lungs are sensitive to, and what causes that burning sensation when you hold your breath for over 30 seconds. Contrary to what most people assume, when you hold your breath and your lungs start burning, it is not because the O2 levels are low, but because the CO2 levels are increasing. When the CO2 in the lungs increases too much it results in respiratory acidosis. In the Apollo 13 mission, they had plenty of O2, but they also were at risk of having too much CO2 (since the scrubbers in that part of the ship were only designed to remove the CO2 exhaled by two people and not three). So the big emergency was trying to find a way to get the CO2 out of their air and down to a safe level.

    Interestingly, your lungs will not detect a lack of O2. If the O2 was totally removed from the air, and replaced with something inert like nitrogen, you would slowly go unconscious and eventually die. In fact, various states are considering using this method to execute death row inmates (simply removing the O2 from the air) since it would be humane and nearly fool-proof.

    • Do lungs detect things? Is the brain involved?
      • Re: (Score:2, Funny)

        by Anonymous Coward

        Do finger detect hammer? Is the brain involved?

      • by EvilSS ( 557649 )
        No (it's actually chemoreceptor nerve clusters in found in the circulatory system and cerebral-spinal system not the lungs), and yes (but in the brain stem, so it's a primitive, core function).
      • by ceoyoyo ( 59147 )

        The breathing reflex is controlled in the brainstem. The chemoreceptors that feed the system are located in the aorta, carotids, and brainstem.

        https://en.wikipedia.org/wiki/... [wikipedia.org]

    • by Rei ( 128717 ) on Tuesday July 09, 2019 @05:23AM (#58894914) Homepage

      Indeed, anoxia without associated hypercapnia is probably the most painless way to die. It's so painless that it's insidious, having caused a number of plane crashes over the years. Mild hypoxia leads to symptoms similar to alcohol consumption - impaired decision making, impaired motor skills, etc. The impaired decision making makes it even harder for a person to notice and react to their hypoxic state. As the oxygen partial pressure continues to fall, it steadily progresses from there to loss of consciousness, and eventually, death.

      It's hypercapnia that makes you suffer when you hold your breath or breathe air in a confined space.

    • by EvilSS ( 557649 ) on Tuesday July 09, 2019 @10:41AM (#58895932)

      Interestingly, your lungs will not detect a lack of O2.

      This isn't entirely true. You are correct that you won't get that panic-burning sensation when hypoxia occurs without CO2 buildup, however your body can detect, via the peripheral chemoreceptors, low O2 levels without a corresponding increase in CO2 concentrations in the blood, and it will increase the respiratory effort accordingly. This can be observed during exercise or when visiting high altitudes.

  • Plants plants (Score:5, Interesting)

    by bonedonut ( 4687707 ) on Monday July 08, 2019 @11:53PM (#58894302)
    and more plants! In every room of the house/school/office/store/jail
    • and more plants! In every room of the house/school/office/store/jail

      The wrong type of plants are the reason that got a lot of folks into jail in the first place.

      On the other hand, in a chilled out prison population, there might be less violence.

  • FTFA: "In the real world, CO2 concentrations in office buildings normally don’t exceed 1,000 ppm, except in meeting rooms, when groups of people gather for extended periods of time."

    Sorry, I will be unable to attend your all-day PI Planning session because it will hurt my brain.

    • Re: (Score:2, Interesting)

      by Anonymous Coward

      Maybe this explains why the worst decisions are made in meeting rooms.

  • CO2 Cycle ... (Score:2, Informative)

    by Anonymous Coward

    When the human body "combusts" hydrocarbons it breaks carbon chains and replaces them with O2 attached to each carbon atom. This is the same process that occurs whenever you "set fire" to a carbon-chain compound (gasoline, diesel fuel, paper, whatever). The co2 that is produced gets "dissolved" in the water that comprises most of each "ugly bag of mostly water". This forms Bicarbonate and Hydrogen ions. In the lungs the bicarbonate is converted back to a gasseous state and "migrates" across the membrane

  • by nospam007 ( 722110 ) * on Tuesday July 09, 2019 @04:54AM (#58894848)

    "Indoor Carbon Dioxide Levels Could Be a Health Hazard"

    So we halve the Dioxide and use Carbon Monoxide, then we won't have to bother anymore.

  • Either drink still water, or move outside with your Coke can.
    • Being curious, I looked up the numbers. One can of Coke has 2.2 grams of CO2.

      Humans exhale about 1 kg/day, so it takes about 3 minutes to exhale a similar amount as contained in one can of Coke.

  • that if you jump in water your skin could become wet...
  • I once got a light rail train that was absolutely packed. I could not breath, and almost passed out.
  • Makes sense. CO2 is more dense than dry air and would tend to settle into your parent's basement.

  • Want to make people go crazy instantly, just release a small quantity of methane in an enclosed spaces like an elevator or a meeting room. This is easily naturally produced by the mastication and digestion of quantities of fibrous material like beans - the magical fruit.
  • I'm nearly 40, and it's just amazing how the very same lessons just keep being forgotten. I can't imagine how frustrating this will be for me when I'm 80.

    It's not the CO2, it's not the pollution, it's not the cigarette smoke, it's not the junk food, it's not the sugar, it's not the fat, it's not the carbs, it's not the sedentary, it's not the manual labour, it's not the indoors, it's not the UV rays, it's not the alcohol, it's not the drugs.

    It's the always CO2, it's the always pollution, it's the always ev

  • It won't happen in my lifetime, but perhaps in the lifetime of babies being born now atmospheric CO2 could reach 1000 ppm. So opening a window won't lower the CO2 concentration below 1000 ppm. Will we install CO2 scrubbers in our homes?
  • Is there a causal hypothesis about the adversarial health effects of increased levels of CO2? What causal, physiological, reasoning makes that people suspect slightly increased CO2 levels? The CO2 fraction in the lungs is under normal circumstances much higher than the elevated CO2 fractions that are discussed here (50,000 vs around 1000 ppm). In humans, under normal circumstances, the blood level of CO2 is the input of the physiological control system of ventilation and perfusion, so a slight increase of

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