Surprising Carbon Dioxide Levels - Using Recirculate on Long Trips

[rstcso]

I read an article the other day about how quickly carbon dioxide levels can climb in a car when recirculating is turned on. Higher levels can lead to headaches, drowsiness, fatigue, and more. Especially not good when on long trips.

My wife and I regularly drive to Wisconsin, driving 18 hours straight through. She's about to embark on a 5k miles' trip on her own, So I bought this CO/CO2 monitor off Amazon. Part of the display flashes green when the CO2 level is less than 700ppm, flash yellow when between 700-1500ppm, and flash red and sound an alarm when over 1500ppm. Playing with it Testing yesterday in my closed-door home office, the CO2 level was close to 1200ppm, so I opened my window and it started dropping some, but stayed above 900. Thinking something must be wrong, I set it outside in the shade, where the level dropped and stayed just over 400, which I read was "normal" for being outside.

I opened all the windows in the house and the levels inside dropped to under 500 after an hour or so, but closed them after the outside temp climbed well past 80. This morning I came upstairs to my office and turned it on. It's currently flashing yellow with a reading of 918 to start my day. Unfortunately, it's still warm outside, so not opening the windows, yet.

She will be taking the monitor with her (I hope she uses it). We've talked about switching off the recirculate once the car cools off to have some fresh air.

I'd never thought about CO2 levels being so high in our home, but here in central Texas, it stays closed up most of the time with the A/C on.

We are constantly warned about, CO levels, but have you checked the CO2 levels where you work, live, and drive?

 

[bioilcurious]

It's kind of funny— I just went through this whole ordeal with my house. I was considering EFIS/stucco siding, but some people were telling me it would make my old house too airtight. So, I bought one of those meters, and I found that my house is in the 400-500 range when it’s really windy, and in the 600-900 range with no wind. If I close a door in a bedroom and have 3 people and a dog, within about an hour it would be at 1300.


Basically, I discovered that if you make the house too airtight, you need to install an ERV (Energy Recovery Ventilator) or an HRV (Heat Recovery Ventilator) to bring fresh air into the house without significantly changing the air temperature.


For now, though, I’m sticking with my old aluminum siding. Also I never use the air recirculate on my vehicles because it makes the air feel really "stuffy".

 

[OneLonelyBurrito]

I read an article the other day about how quickly carbon dioxide levels can climb in a car when recirculating is turned on. Higher levels can lead to headaches, drowsiness, fatigue, and more. Especially not good when on long trips.

My wife and I regularly drive to Wisconsin, driving 18 hours straight through. She's about to embark on a 5k miles' trip on her own, So I bought this CO/CO2 monitor off Amazon. Part of the display flashes green when the CO2 level is less than 700ppm, flash yellow when between 700-1500ppm, and flash red and sound an alarm when over 1500ppm. Playing with it Testing yesterday in my closed-door home office, the CO2 level was close to 1200ppm, so I opened my window and it started dropping some, but stayed above 900. Thinking something must be wrong, I set it outside in the shade, where the level dropped and stayed just over 400, which I read was "normal" for being outside.

I opened all the windows in the house and the levels inside dropped to under 500 after an hour or so, but closed them after the outside temp climbed well past 80. This morning I came upstairs to my office and turned it on. It's currently flashing yellow with a reading of 918 to start my day. Unfortunately, it's still warm outside, so not opening the windows, yet.

She will be taking the monitor with her (I hope she uses it). We've talked about switching off the recirculate once the car cools off to have some fresh air.

I'd never thought about CO2 levels being so high in our home, but here in central Texas, it stays closed up most of the time with the A/C on.

We are constantly warned about, CO levels, but have you checked the CO2 levels where you work, live, and drive?

I did recently listen/watch, I don't remember if it was a YouTube video or podcast, something on this topic. It was in a different context than high CO2 being directly harmful to one's health, it was more about airborne infectious diseases. But basically the gist of it was the person was using a CO2 monitor on his wrist as a proxy for whether the indoor space had adequate ventilation. If the CO2 level were getting too high, basically the room didn't have adequate ventilation and the risk of airborne disease spreading was higher and precautions should be taken.

 

[rstcso]

I did recently listen/watch, I don't remember if it was a YouTube video or podcast, something on this topic. It was in a different context than high CO2 being directly harmful to one's health, it was more about airborne infectious diseases. But basically the gist of it was the person was using a CO2 monitor on his wrist as a proxy for whether the indoor space had adequate ventilation. If the CO2 level were getting too high, basically the room didn't have adequate ventilation and the risk of airborne disease spreading was higher and precautions should be taken.

The article I read linked to the one you're referencing. It was a study done in regards to a SARS virus. I saw another related to police and their K-9 officers high exposure to CO2.

 

[dnewton3]

https://www.osha.gov/annotated-pels/table-z-1
https://www.cdc.gov/niosh/npg/npgd0103.html

Permissible CO2 limits are much higher than what you've been led to believe. I'm not saying it's a bad thing to reduce exposure, but at 1500 ppm, to perceive it's dangerous is a bit of marketing gas-lighting.

IDLH = 40,000 ppm
STEL = 30,000 ppm
TWA = 5,000 ppm

At 1,500 ppm, there is no discernible effect on human performance or safety whatsoever.

 

[EvoMan]

I think that monitoring oxygen levels would be more important. When I worked on the Space Shuttle program, we always monitored the oxygen levels when we did any kind of confined space work. I don’t remember monitoring CO2 levels.

 

[Vercingetorix]

Dihydrogen monoxide is also very dangerous.

 

[bioilcurious]

At 1,500 ppm, there is no discernible effect on human performance or safety whatsoever.

On the one hand you have studies like these. Which seem to indicate some type of cognitive decline above 1000 ppm of CO2.
https://www.sciencedirect.com/science/article/pii/S036013232300358X
https://pubmed.ncbi.nlm.nih.gov/23008272/
https://pubmed.ncbi.nlm.nih.gov/30172928/

Then on the other hand you have studies like these that show no cognitive decline or performance below 2100 or 1500.
https://www.sciencedirect.com/science/article/pii/S0360132323009940
https://www.rehva.eu/rehva-journal/...arbon-dioxide-levels-on-cognitive-performance

The problem is how the studies are conducted. Essentially, you can have a high-ventilation environment and inject direct CO2, and not see any negative effects. Alternatively, you can have a more realistic environment where rising CO2 levels could be a sign of poor airflow, which may also indicate the presence of other pollutants. This might suggest that CO2 is not the sole issue. However, I am not qualified to say for certain what it all means.

Most people cite the Canadians long term exposure limit of 1000ppm of CO2. They claim that is in line with other countries like korea, Japan, France, Norway, Portugal, and Germany. Also, The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommends maintaining indoor CO2 levels no greater than 700 ppm above ambient levels (assumed to range between 300 and 500 ppm).
https://www.canada.ca/en/health-canada/services/publications/healthy-living/carbon-dioxide-home.html

 

[rstcso]

Dihydrogen monoxide is also very dangerous.

Especially if in it over your head and can't swim.

 

[rstcso]

The instructions that came with it show how to modify the default alarm settings, but I'll need to get out my Sherlock Holmes spyglass in order to read the tiny print.

 

[Pablo]

I think that monitoring oxygen levels would be more important.

A good point.

 

[alarmguy]

Wow, great thread. Maybe part of the explanation on why our new home has an air exchange system built into the HVAC. When the unit turns on there is a second air duct inside the main air intake that has a metal "flap"and when the unit kicks on the flap solenoid controlled opens up and draws in outside air that gets mixed in with the house air.

I would wonder how necessary it was and if I should disconnect it as it draws in hot air in the summers and cold in the winters. Makes more sense now. For the record I wouldnt disconnect it.

Now I have to see if @rstcso gets me to part with $50 I love ALL things instrumentation and wow I do at times start zoning out in the car for no reason. Once in a great while I pull over and have my wife drive for a short period.

 

[50yr Street Mech]

Never crossed my mind about that, but it's true. You're breathin the same air over and over. I like to drive with my window cracked open a bit for some reason, unless it's raining/snowing. Always did. Wow, cars can be that airtight. The A/C works better on re-circulate, which makes total sense. No wonder people get groggy behind the wheel and open all the windows. Who am I kidding, a car ride puts me to sleep anyway .....always did.

 

[I<3oil]

Yep, I rarely use recirc. Usually only if its 90*+ and first getting into the car to help cool it off better.

 

[JTK]

It's interesting to see what the PPM concentration is with CO2, but it's the displacement of O2 that matters for us breathers vs any toxicity of the CO2 itself.

In my line of work, cryo air seperation. We use adsorption beds to capture the CO2 in the inlet air stream. If you don't get it out, it freezes solid and plugs the heat exchangers and distillation columns up.

 

[rstcso]

Now I have to see if @rstcso gets me to part with $50 I love ALL things instrumentation and wow I do at times start zoning out in the car for no reason. Once in a great while I pull over and have my wife drive for a short period.

This is the reason I try very hard to stay out of the New Tool threads.

 

[Sequoiasoon]

Never crossed my mind about that, but it's true. You're breathin the same air over and over. I like to drive with my window cracked open a bit for some reason, unless it's raining/snowing. Always did. Wow, cars can be that airtight. The A/C works better on re-circulate, which makes total sense. No wonder people get groggy behind the wheel and open all the windows. Who am I kidding, a car ride puts me to sleep anyway .....always did.

That's why they make the ventshades for the windows. You can leave them cracked open in rain/snow whatever and not get wet.

My cars are normally on fresh intake. I will put to recirculate when stuck in traffic with vehicles emitting diesel smoke, poor running gas versions etc. I'll take the higher CO2 over the horrible exhaust CO.

 

[rstcso]

Yep, I rarely use recirc. Usually only if its 90*+ and first getting into the car to help cool it off better.

I don't think ours has been turned off since buying the car a few months ago, including a 4k mile round-trip to CT. It will be now.

Driving in Austin traffic during the summer, it wouldn't be surprising to look at another driver stuck next to you and it be Lucifer himself... with a big smile on his face.

 

[Vercingetorix]

CO2=Road Rage? Honest officer it wasn’t my fault, it was the carbon dioxide.

 

[97prizm]

I read an article the other day about how quickly carbon dioxide levels can climb in a car when recirculating is turned on. Higher levels can lead to headaches, drowsiness, fatigue, and more. Especially not good when on long trips.

My wife and I regularly drive to Wisconsin, driving 18 hours straight through. She's about to embark on a 5k miles' trip on her own, So I bought this CO/CO2 monitor off Amazon. Part of the display flashes green when the CO2 level is less than 700ppm, flash yellow when between 700-1500ppm, and flash red and sound an alarm when over 1500ppm. Playing with it Testing yesterday in my closed-door home office, the CO2 level was close to 1200ppm, so I opened my window and it started dropping some, but stayed above 900. Thinking something must be wrong, I set it outside in the shade, where the level dropped and stayed just over 400, which I read was "normal" for being outside.

I opened all the windows in the house and the levels inside dropped to under 500 after an hour or so, but closed them after the outside temp climbed well past 80. This morning I came upstairs to my office and turned it on. It's currently flashing yellow with a reading of 918 to start my day. Unfortunately, it's still warm outside, so not opening the windows, yet.

She will be taking the monitor with her (I hope she uses it). We've talked about switching off the recirculate once the car cools off to have some fresh air.

I'd never thought about CO2 levels being so high in our home, but here in central Texas, it stays closed up most of the time with the A/C on.

We are constantly warned about, CO levels, but have you checked the CO2 levels where you work, live, and drive?

Co and co2 shouldn't be high while driving. I've never heard of this being an issue