Surprising Carbon Dioxide Levels - Using Recirculate on Long Trips

[Tom NJ]

Apparently I bought a different one than you I bought this one from the OP's link:

CO/CO2 meter

The battery on this one only lasts about 16 hours if left on. I think these are meant to remain powered off until taking a reading.

My furnace coming on only closes doors that are a few inches open, like to allow a cat entrance & exit from the bedroom.

 

[Doc8404]

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.

As a safety professional, I appreciate this post! You saved me a lot of research and typing.

 

[alarmguy]

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.

This caught my attention but those high numbers posted are for 10 minute exposure and the lower TWA is for 8 hour exposure. Most likely posted because this is OSHA which is for work places.
@bioilcurious might be a bit more on game posting residential recommendations which is 24 hour exposure limit of 1000 ppm
Mentioned in the link is other developed nations recommend or require CO2 - 600 to 1000 PPM

Also the "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)." So this will be under the 1500 PPM as well.

I do think overall, if CO2 readings are high that it is showing not enough air exchange is taking place and levels of other contaminants would be high as well. So for what we call a "sick" house. We our new meter we run 700 to 1100 (only had it a few days now) being its a new house, our HVAC does exchange air when the system turns on, as a roof top air intake and duct work feeds into the system intake. A flap opens up to let fresh air in when the unit turns on. I never saw this before in any home until we moved here in 2023

This is the link I used for this post from @bioilcurious
https://www.canada.ca/en/health-canada/services/publications/healthy-living/carbon-dioxide-home.html


__
PS to @Doc8404

 

[alarmguy]

And you’re basing all this on a $50 amazon meter that you can’t cross check or calibrate? The golden rule is first verify your measurement system.

What does it read at the tailpipe? In open air?

It's easy to check that it is reasonably in the ballpark for a consumer item. All you have to do is place the meter outdoors and you should get a reading of around 400PPM which is the outdoor level of CO2
Actually using outdoor air is how you re-calabrate many CO2 devices

 

[Hohn]

It's easy to check that it is reasonably in the ballpark for a consumer item. All you have to do is place the meter outdoors and you should get a reading of around 400PPM which is the outdoor level of CO2
Actually using outdoor air is how you re-calabrate many CO2 devices

Yes, I'd expect an local reading between 380 and 415.

 

[alarmguy]

So did I. In my case I want to monitor the CO2 levels from our ventless propane fireplace so I can know how long to run it in the evening.

That would be cool to watch when the fireplace is on. Also I am sure you have a plug in CO detector? Im not sure my family would be here today if not for one and the one I had was before most people knew they existed in the early 1990's

Since we are concerned about air quality with these CO2 meters, very cool that the OP brought it up, Im fascinated by gauges and meters, enjoying it. But I also hope everyone here and families have a CO (carbon monoxide) detector if any fossil fuel devices are in the house.

 

[Tom NJ]

Also I am sure you have a plug in CO detector?

Multiple plug ins.

 

[alarmguy]

Multiple plug ins.

Yeah here too and one of those that I have has the digital read out. I like that idea as if even low levels of CO are around but not enough to trigger the alarm I would want to know about it.

 

[Cujet]

This thread inspired me to purchase the OP's meter from the Amazon link. Mostly because I can also use it to measure CO rise in my airplane. The meter arrived yesterday, I charged it and put it in the bedroom. The alarm started blaring at midnight, CO2 over 2000ppm.

Of course, these cheap meters are generally not particularly accurate, they are good for measuring trends. The published accuracy is 50ppm +/- 5%, and I question that. Know that these inexpensive meters use a 'dust sensor' reconfigured to measure CO2. This unit does not use a real NDIR CO2 sensor, which are both expensive and power hungry.

A hobbyist NDIR CO2 sensor costs more than this inexpensive meter. I did find some similar portable units that claim to have an NDIR sensor.

Anyway, it's useful and fun to play with. Might go fly today or tomorrow and measure CO levels in the plane.

 

[Snagglefoot]

Our house is so tight that when the furnace kicks on it shuts doors. My new meter is reading 400-410 most of the time, same as atmospheric, but if I breath on it it shoots up over 2,000. I read one should not run a ventless propane fireplace more than two hours at a time, which is what we have been practicing, and now I can test it. We run it for aesthetics more than heat, but it does warm the woogies.

Interesting comment on the doors. It might also be caused by a blockage in your return air ducts, such a furniture in the way.

 

[Snagglefoot]

100% different things. You won't have a short term medical problem with CO2 up to maybe 5000PPM. Doesn't mean I want to breath anywhere near that all day. Makes you feel poorly.

I have this meter - have been using it in hotels. So far the worst has been about 1200PPM, so not great really. Best like 450 PPM (basically same as outside).

The observatory at Mauna Loa in Hawaii is recording just over 400 ppm CO2. How’s that for calibration? The average for September was 425.48 ppm.

 

[SwampSurvivor]

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.

We just had a new furnace put in. The old furnace had a duct that went into the attic to pull air from the attic. I thought it would be a good idea to not hook that up because it would pull outside air in to run the furnace. Furnace guy advised against it but did it anyway.

After a whole debacle with the utility company (long story ...) we got the furnace working and kept smelling a musty smell when the furnace ran. I thought it was the duct work since our AC drain plugged up over the summer. But I pulled the duct work apart and apart from a ton of dust, no real bad smells in there.

Then I went into the crawlspace to check and that was the smell. Turns out our house is so well sealed that instead of pulling in air through the windows/doors, it was pulling it from the crawlspace! The hole in the floor (which has to be big for code) where the gas passes through to the furnace was one of the holes - I patched that up and it still kept doing it. Turns out it was then pulling in from the sinks. Ended up hooking it back up to the attic

 

[Snagglefoot]

High efficiency furnaces and boilers will have a sealed dedicated outside air intake for combustion air. Mine simply goes the 10 feet or so and exits through a side wall. In our area, its in the building code.

 

[Tom NJ]

Interesting comment on the doors. It might also be caused by a blockage in your return air ducts, such a furniture in the way.

Good point but my return duct is wide open, and I use a Filtrete 1900 20x30 filter which has very good flow.

 

[AZjeff]

Someone take their meter on a full commercial flight and get back to us.

 

[Cujet]

Someone take their meter on a full commercial flight and get back to us.

I'll take my meter on my private flight this AM. Will be interesting to see the numbers.

 

[Cujet]

I'll take my meter on my private flight this AM. Will be interesting to see the numbers.

CO2 varied a bit during flight. 405 to 420. vents open or closed did not seem to change things.
CO hovered around 0 with the vents open, and as high as 20 on final. Interestingly, the faster I fly the lower the CO numbers. Mach 2.3, er, ah, 145kts, = 0ppm CO. 103kts, maneuvering speed (for turbulence) is 5 to 9ppm.

 

[Owen Lucas]

Mach 2.3

Take me on a flight please!

 

[FordP3]

CO2 varied a bit during flight. 405 to 420. vents open or closed did not seem to change things.
CO hovered around 0 with the vents open, and as high as 20 on final. Interestingly, the faster I fly the lower the CO numbers. Mach 2.3, er, ah, 145kts, = 0ppm CO. 103kts, maneuvering speed (for turbulence) is 5 to 9ppm.
View attachment 308784

Thanks for the reply. I was curious about this. It would also be interesting to see what the levels would be in a full commercial jet with 250 or so passengers.

 

[rstsco]

CO2 varied a bit during flight. 405 to 420. vents open or closed did not seem to change things.
CO hovered around 0 with the vents open, and as high as 20 on final. Interestingly, the faster I fly the lower the CO numbers. Mach 2.3, er, ah, 145kts, = 0ppm CO. 103kts, maneuvering speed (for turbulence) is 5 to 9ppm.

Doesn't sound like you're in a pressurized cabin, or even well sealed.

I'm flying my WFM desk and have 0000 CO, but 1387 CO2... and climbing. I guess I need to stop breathing. Went with option B... turned it off before the alarm started sounding.