CO2! It’s surprising how fast CO2 accumulates indoors when windows are closed and air con running. The annual Californian wild fires have started and the smoke plumes are covering parts of Silicon Valley inc Mountain View where I live and now work from during Covid quarantine.
Earlier this week I was feeling sluggish and turned on my CO2 sensor to check the state of CO2 build up indoors. I followed EPA‘s and CDC‘s wildfire recommendations to lock doors & windows and run the air conditioner. I got a shock! CO2 levels reached 2,430 ppm!
An hour later I decided to venture outside. Even tho the sky had red/black clouds, I was pleasantly surprised it was ok to breath outside. I took the CO2 meter with me and confirmed my suspicion. CO2 levels outdoor were at 447 ppm. The pictures below were taken at the time.
On a good clean day in Mountain View, I’ve recorded CO2 levels around 300 ppm.
Why was CO2 so high indoors? Lack of ventilation. You breath out CO2, house appliances also produce CO2 etc, and yes it accumulates in the home when doors and windows are closed. The kitchen is notorious for generating a lot of CO2.
There’s also the “sick building syndrome” which might play a role but I don’t have enough data on that yet to comment further. However a lot has been written about this online and proposals to move towards green building designs.
What removes CO2 from homes?
Windows and Plants (Photosynthesis) only. Air Purifiers and Fans do nothing. Have heavy duty ones in the room and nada.
Using Plants would be an interesting experiment to work out the volume of photosynthesis required to make this work. I know different plants have different capabilities. Currently I only have 1 plant in each room and I know that’s not enough. Furthermore, photosynthesis only happens in sunlight.
CO2 sensors aren’t included in air filtering machines. I have 2 big machines filtering air with HEPA filters etc. and they stay quiet while my dedicated CO2 device screams.
I use Apple’s Weather app, AirNow and PurpleAir. AirNow is meant to be the most accurate of the lot using high grade sensors. (read below on sensors)
All these online weather apps are either reporting from a region not near me (downtown Mountain View) or are delayed (not real time). Even the highly acclaimed AirNow is 3 hours behind. You can trace it’s data source online quite easily.
The lesson here?
CO2 is an odorless and colorless gas so you won’t know if it’s affecting you till it’s too late.
Use your own judgement based on your own CO2 devices when to ventilate the house.
Most of all, get some fresh air.
My CO2 Device
This is a non-dispersive infrared CO2 sensor to measure the levels of carbon dioxide. It’s a well known fact that high levels of carbon dioxide impairs human cognition. There is enough scientific journals in Nature, NIH, etc, on this topic. Google it.
Why this device? It uses a specific wavelengths of light to measure the amount of CO2 in the air. Much more precise and reliable than the cheaper electrochemical CO2 sensors. Order it from Amazon.
Stay safe during the annual California wild fires!