CO2 and Indoor Air Quality, school me please

[Poindexter]

I have a CO2 problem. Typically my clean outdoor air carries 200-300 ppm CO2. When I am home and exhaling CO2, I need to run my HRV 40 minutes per hour. At that setting, my indoor CO2 usually runs in the 600s of CO2 ppm.

Today, with hazardous outdoor air quality I am seeing 700s ppm CO2 indoors.

Here is three pics, I'll add discussion in the next post.

 

[Poindexter]

Fundamentally, I am running everything I got at full throttle.

The sensor at "NCore" run by the EPA (and closest to my home) doesn't publish CO2. I don't know if they measure CO2.

Currently two wildfires burning within 30 miles of town. There are a couple directions the wind "could" blow from to relieve the city of wildfire smoke.

The intake filter on the HRV captures 50-100mcg/m3 of PM2.5. The box fan on the floor with one MERV 13 taped to the back draws 0.5 amps continuous. The fridge sized cabinet with 6 of MERV13 in it draws 0.6 amps continuous. My standalone dehumidifier is drawing 5.5 amps on about a 50% duty cycle to maintain 40%RH.

I could turn up the HRV to continuous to flush out more CO2, but my particle counts will start going up.

So I am looking to add some kind of CO2 capture to my IAQ suite.

 

[Poindexter]

Before you start selling me on house plants, please understand that so far this summer I have killed two dill, 2 thyme, one sage, 2 oregano and a rosemary. These were all on my kitchen counter next to my cutting board.

NASA did find that enough plants can scrub CO2 from human habitation, but they needed 10-1000 plants per square meter of floor.

https://en.wikipedia.org/wiki/NASA_Clean_Air_Study

I hear spider plants are tough and hard to kill. I will get one to see if that is true.

 

[Poindexter]

Well fiddlesticks. I have turned the HRV up to continuous.

 

[stoveliker]

I think you don't need to aim for outdoor CO2 levels indoors.

 

[Poindexter]

@stoveliker , in this thread https://www.hearth.com/talk/threads...d-indoor-air-quality-hearth-com-style.198427/ comma, I busted out my google-fu for this post: https://www.hearth.com/talk/threads...y-hearth-com-style.198427/page-2#post-2675304

In my preference less CO2 is better, some is inevitable. Given my previous findings as linked above, my comfort zone is under 700ppm. Ambient outdoor CO2 in Fairbanks, with no wildfire activity seems to run 200-300 ppm.

I think of CO2 <700ppm as the green zone. 700-800ppm, single yellow. 800-1000 ppm double yellow, over 1000ppm is the well accepted red zone.

Like PM2.5 this is an airborne pollutant I would rather keep managed in the green zone rather than try to come up with something from scratch when I am already in the red zone.

I did also have this observation in a thread about HRV systems. Running the indoor CO2 up to 1660ppm (measured) when my first CO2 detector came in the mail got my undivided attention. I had been running the HRV one hour per day as instructed by the landlord. I had been grumpy and not sleeping good and constant headaches for more than a week. Once I got the place aired out and the CO2 level under control all that cleared up save for my baseline cantankerousness.

 

[stoveliker]

Yes but all the URLs there basically say <800 is okay, recommended etc.

 

[Poindexter]

I am not sure which sensor was used to come up with the PM2.5 count of 1160 mcg/m3 this morning, but it is believable.

I am kinda leaning towards adding capacity to my particle filters for days like these. With the toolbox I have just pumping out exhaled CO2 and dealing with incoming particles seems like the path of least resistance.

I am very open to points of view from folks with different skillsets.

 

[EbS-P]

I regularly see 900 ppm CO2 measurements on my cheap meter. I’d like it to be lower but I don’t have a good way yet to bring in filtered air. In your case I see your elevated CO2 levels as not typical but how many days a year will you see them? Sounds like you. Need a co2 scrubber. How about supplemental oxygen for really bad days. How much would that cost?

 

[zrock]

not something i ever check for and im far from knowledgeable on this subject, but first thing that came to mind is what inside your home is increasing the level, and why is your landlord telling you how to run it? First thing that comes to mind is something in the home.

 

[begreen]

I am not sure which sensor was used to come up with the PM2.5 count of 1160 mcg/m3 this morning, but it is believable.

I am kinda leaning towards adding capacity to my particle filters for days like these. With the toolbox I have just pumping out exhaled CO2 and dealing with incoming particles seems like the path of least resistance.

I am very open to points of view from folks with different skillsets.

View attachment 328129

And I thought New Dehli with an over 600 reading was bad. That's awful.

 

[Poindexter]

And I thought New Dehli with an over 600 reading was bad. That's awful.

I am noticing the wildfire smoke here this summer is not evenly distributed. There is an over all minimum, and perhaps a bit of an average, but there are also some remarkably thick tendrils slithering around in the murk.

To me 1166 mcg/m3 local one one sensor is believable, but I doubt the sensor of the homeowner is actually calibrated to read accurately at that high of a concentration.

It is awful.

 

[EbS-P]

I’ve been thinking more. They burn the pine plantations here. We will get ash fallout from it. Max we have 4-5 days a year. Indoor CO2 below 1000 ppm might make for an uncomfortable 5 days for me but probably not unhealthy.

Parts of the world will undoubtedly see many more than 5 days. The answer it’s filtered outside air. At multiple stage filtration may be needed. Have you read anything about clean room design for semiconductor manufacturing? Probably some decent information to be gained.

 

[peakbagger]

FWIW,I looked into CO2 scrubbers for an industrial HVAC issue about 20 years ago. It was sealed insulated small room for a process control computer. Operation employees tended to hang out in their during their shifts as it could be brutal outside the room especially in summer. There was gasketed stainless steel door to access the room. The outside environment was hot wet and nasty. The computer needed clean air cool air but its location precluded bringing in outside air to pressurize the room. The room had a AC unit that just recirculated air around and round. The only fresh air was leakage and when the door opened. It smelled like a locker room inside and there was valid concern about air quality including CO2. I was asked to find a CO2 scrubber for the room and I never found one that met the requirements. There were amine based units but way out of the budget. The management decision was to ignore it and ban workers from hanging out in it.

At the pulp mill, there were a couple of rooms for Distributed Control Systems with walls of racks of local I/O panels and the main processors, the atmosphere even outside the buildings was corrosive and unless the rooms were supplied treated air, the electronics didnt last long. We installed deep bed scrubbers which usually were activated carbon based with some potassium permanganate added to it. The air volume of the room was circulated through the beds continuously with a small outside vent upstream of the carbon bed to pressurize the space. If the rooms were well sealed, the doors were kept shut and the system maintained they worked well but it was a bear to retrofit the systems to existing rooms. The filter media had to be changed about every 3 months. The media supplier supplied special test coupons that consisted of strips of copper, silver and gold that were placed in equipment cabinets and they could send them out to the lab and determine the extent of corrosion and link that the media life.

 

[begreen]

I am noticing the wildfire smoke here this summer is not evenly distributed. There is an over all minimum, and perhaps a bit of an average, but there are also some remarkably thick tendrils slithering around in the murk.

To me 1166 mcg/m3 local one one sensor is believable, but I doubt the sensor of the homeowner is actually calibrated to read accurately at that high of a concentration.

It is awful.

Unfortunately, this is going to get worse. I've read that the temperature swings and extremes will be felt in the arctic regions the most. The major loss of arctic sea ice in June 2024 is most disturbing. So are the expected and unexpected effects of permafrost melt. 2023 was a record breaking year for global temperatures and 2024 is already on track to beat that record easily.

 

[semipro]

I wouldn't give up yet on the plants for purifying indoor air. They can also help deal with non-particulate contaminants like formaldehyde.

 

[EbS-P]

I wouldn't give up yet on the plants for purifying indoor air. They can also help deal with non-particulate contaminants like formaldehyde.

You could grow algae

 

[Poindexter]

The media supplier supplied special test coupons that consisted of strips of copper, silver and gold

Currently, the least expensive option seems like it might be good old dirt with a vibrant population of soil bacteria, 'packed' very porous, and another fan to push air through the soil. For my 900sqft x 10 foot ceilings = 9000 cuft I am looking at a flower pot about the size of a sofa, and an even higher electric bill.

The small chemical scrubbers like for the ISS (international space station) are simply out of my budget by big dollars. Big big dollars.

 

[Poindexter]

Throwing a link in here knowing @begreen would probably notice it without me tagging him.

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This is Owen Hanley MD the older. He is retired. His son, Owen Hanley MD the younger is about the same age as my kids, and currently practicing in Fairbanks.

When I got to Fairbanks in May 2008 I had years of experience in bronchoscopy at Duke U pulmonology lung transplant program standing shoulder to shoulder with board certified MD pulmonologists with professorships to go with, evaluating transplant candidates with the err, black serpent of truth. Duke UMC is a fairly prolific lung transplant program.

When I got to Fairbanks in May 2008 I had years of experience in bronchoscopy at UCLA pulmonology lung transplant program standing shoulder to shoulder with board certified MD pulmonologists with professorships to go with, evaluating transplant candidates with the err, black serpent of truth. UCLA is a fairly prolific lung transplant program.

Within two weeks of my arrival I was shoulder to shoulder with Owen the elder for every lung he scoped until retirement. I never got to leave early for the weekend because he always scoped at 1500 on Friday. It was nice to be recognized, but we simply don't have the case volume up here to develop a replacement with the muscle memory I brought to the table when I stepped off the aeroplane.

Owen the elder could have been the director of the lung transplant program at either of Duke or UCLA, 20 years before retirement, if he chose that path. Instead he stayed in Fairbanks and raised Owen the younger. If you take your dream vaca to Alaska, get sick and show up in the Fairbanks ER and meet some doctor named Owen, you are in good hands. There are many other kids in this age cohort who really know their stuff, but I started calling Owen the younger 'doctor' while he was still an MS3.

Owen the elder starts making some claims without footnotes starting around the thirteen minute mark. I personally don't need to look them up, as both of the Owens have my complete trust. FWIW Owen the elder was UCLA MD class of 1964.

 

[gthomas785]

Global average atmospheric CO2 concentration is 426 ppm. If you're really getting 200-300 ppm in your location that's amazing. I'm more suspicious that your meter is defective.

 

[stoveliker]

Yes, in particular given that differences in local outdoor levels around that average seem to be below 10 ppm.

 

[Poindexter]

@gthomas785 and @stoveliker , fair points. I have started taking myself to school today. It seems (preliminarily) like above 3000 meters, above about 10,000 feet altitude, the air above Alaska is pretty much the same as everywhere else on the planet.

I live in a new to me TLA; I live in the ABZ. For atmospheric scientists that is the TLA for the "Arctic Boreal Zone." I am firmly in the boreal portion, but the nearest melting permafrost I know of with a broken building on it is about three miles from the keyboard I am typing on right now. The nearest permafrost that might be melting with no construction on it is about two miles.

Below 3000 meters altitude there is a pitched battle between plants adapted to fix a lot of atmospheric carbon very quickly during short growing seasons, and carbon coming out of melting permafrost into the air.

All of my outdoor CO2 measurements have been in the summer months when ground level plants are fixing carbon, and I need to find out the warm up time on my CO2 sensor. My outdoor readings are uniformly taken at ten minutes after power up as my Plantower S-50 particle counters need 3-7 minutes to stabilize after power up, but I might be taking readings off my CO2 sensor before it is fully warmed up.

Thanks for the pointers folks.

 

[begreen]

Looks like the air quality around Fairbanks today is excellent though I have not been able to find a good source for the outdoor CO2 readings.

This is an interesting study of the effects on CO2 levels of melting permafrost.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG006044

 

[Poindexter]

Yah, air quality is good today. It has been raining slow and steady for about 36 hours now. I actually have the core of my HRV soaking in the bathtub with hot soapy water for another 2.5 hours today. Once re-installed the book says to run it on high for 48 hours to make sure both the core and the ductwork are dried back down to ambient humidity. I am not too worried about drawing in particles or CO2 at the moment, but I probably will have to run the dehu some.

I did see a paper similar to the one @begreen linked speculating about the possibility of a somewhat persistent CO2 umbrella over the ABZ below 3k meters might accelerate permafrost melting. I don't know how many scientists are looking at how low level CO2 crosses the 3k meter line to join global circulation, but there is plenty of folks talking about it.

I did find the outdoor intake duct for my HRV system was ~50% occluded. It took longer to run a drop cord than it took to actually vacuum off the intake grating. I am curious to see if it draws measurably less current when I get it put back together.

Sigh, back to class.

 

[Poindexter]

I have been emailing with UAF (University of Alaska at Fairbanks) atmospheric sciences. I got an actionable response today from a professional researcher who is running some CO2 detectors roughly 20 miles outside of town.

They are running equipment that uses 'eddy covariance to measure fluxes of CO2 and CH4.' I had never heard of that, but I am sure it is expensive. The researcher sent me one graph for one week, and demonstrated minimum CO2 concentration in Fairbanks doesn't drop much below 400ppm. It is expected that CO2 concentrations will go up overnight while plants are dormant and human carbon release continues.

Just recently this evening I measured 397ppm CO2 on my front porch with calm winds as the sun went into chill mode and nearby plants stopped actively pulling CO2 out of the air to make edible vegetables.

In the one graph I did receive CO2 concentration 5 meters above grade is notably less than CO2 concentration 2 meters above grade. If you are building new it makes sense to put your HVAC/ HRV/ERV intake as far as reasonable above grade to minimize CO2 intake, system run time and electric bill.