Evaluating Carbon Dioxide at Home with an Aranet4 in Myalgic Encephalomyelitis

An Aranet4 carbon dioxide monitor: A small white square device about the size of a human palm, with an e-ink display showing the PPM of carbon dioxide, the temperature, and the relative humidity.
My new little buddy.

This fall, I acquired an Aranet4 CO2 monitor, with the intention to check ventilation at the dentist’s office, the one place I go where I can’t wear my PAPR. It’s been even more illuminating at home, however, and using it has helped me improve a little.

The documentation with it informed me that a reading in the 400s was typical for outdoor air, and that it was optimal that indoor air be below 1000. During the period of the autumn when we were able to have the house open, we did generally get readings in the 400s or 500s.


We have gas appliances, which produce CO2 in combusting natural gas. Our stove puts off more CO2 than I expected and the furnace less. In my bedroom, two rooms away from the kitchen, the level bumps up to a bit over 1000 cooking a typical meal, but abates effectively over an hour or two; running the oven full tilt for an hour, like to do a pizza on the baking steel, gets well up into the 1400-1500 range in my bedroom and takes some effort to knock down.

Our exhaust setup isn’t the best; we currently have a recirculating range hood. The previous owners of our house remodeled the kitchen, removed the exhaust fan ductwork and replaced that with a over-the-range microwave with one of those terrible little recirculating fans.

We had planned to replace that with a proper exhaust hood but then pandemic, so we have a hood that can be either recirculating or hooked to ductwork, have it set up to do the former and are waiting until we can have someone in to do the ductwork for the latter.

Human Output

I’ve historically kept my bedroom door closed at night to prevent feline incursions from awakening me. I run an oxygen concentrator in another room at night with the hose running into the bedroom. There’s also an Austin Air Bedroom Machine air purifier running constantly at the lowest setting in my room, but in terms of gases, that only acts on NO2 and doesn’t affect CO2.

Using the Aranet4 to evaluate that setup, I found I was ending up in the 1300s by the end of the night.

Running the furnace fan to continuously ventilate the room seemed like an easy fix; I wear earplugs at night so the sound is tolerable.

Now when I wake up, after running the furnace fan all night, the level is in the 700s, about where it was at the start of the night.

I have been surprised to find that small change has made a little bit of a difference in my energy levels. And at my degree of debility, a little boost means a lot.

What’s been most interesting is that in that shift, my resting heart rate seems to have landed at a new, higher normal. My normal nighttime reading, not in PEM, used to be 58-59; now it’s more like 63-66.

At first when it was coming back in the high 60s at night, I thought I was just in PEM, and for a bit I definitely was; my heart rate is quite variable based on my respirations, and the worse I’m doing the more it varies in that way. For a while that strong variability was what I was seeing, and I knew it was PEM based on the difficulty of getting my heart rate to settle enough so I could get a reading.

But it’s been a few weeks now, and with readings in the mid-60s most days, I’m pretty convinced now that I’m at a new normal and it aligns with the change in ventilation.

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1 Response to Evaluating Carbon Dioxide at Home with an Aranet4 in Myalgic Encephalomyelitis

  1. Inge says:

    Interesting – without measuring, I cannot sleep without the window open and doors open, only a little bit when it is cold – and I sleep worse when it gets freezing and I have to let the CH running all night. The boiler is in the loft, so nothing gets in the rooms of my bungalow. My cat is quite good, but perhaps once a month she is waking me up. I can live with this.

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