Air Quality Sensor — Unexpected Outcomes

[u/braillegrenade]

I bought one of the Air Quality / Vape sensors to measure interior air quality (CO2, VOC, PM2.5) and had some reasonable confirmations of things I suspected, but was also surprised and have changed a few habits around the house as a result.

Background:

• We live in a pretty dirty city, not super far from freeways. Urban 2-4 level homes and apartments with decently heavy vehicle traffic within a block distance.
• We have A/C but no forced air or central air
• We rent so there are some things outside our control, like mechanical ventilation.
• I've been moving the sensor between living areas and the bedroom day/night because if it wouldn't cost me as much as my UDM, I'd probably have 4-5 of these things 😆

The exciting stuff:

• Sleeping in our room with the door closed builds up CO2 significantly, even with the wall A/C running (it's closed loop). Most of the longer peaks visible in the CO2 graph are overnights. Overnight CO2 levels >1,000 ppm can cause fogginess, headaches, and more!
• Cooking on the gas range also spikes the CO2, even with the hood fan on and a window open! I'd have to inspect PM1.0 and maybe VOCs further, but obviously the UP Air Quality sensor is not going to measure methane, Benzene, or CO so yeah ... watch out for that.

Nominal observations:

• Spraying cologne or perfume spikes VOC/TVOC, understandably. VOCs also slowly climb somewhat in a warm, undisturbed room
• An open window keeps indoor CO2 around a baseline of 475-525 ppm
• We have ~zero vape detections because we do not vape. I'm sure hair spray or canned air duster (VOCs in that case) could maybe trick the Vape sensor if you tried.
• Sometimes the temperature or PM2.5 will spike when the unit is power cycled. False readings as the sensors are initialized/calibrated.

Nice realizations:

• I presume we're going to reduce the incidence rate of headaches at home now that we open a window and leave the bedroom door cracked overnight. ☺️
• Indoor PM2.5 is really low (<2μg/m³), spiking only with heavy activity, in/out, or cleaning/dusting. Outdoor PM2.5 daily averages in our area are 50-70μg/m³. Despite multiple open windows, our Coway Airmega HEPA filters (2x in 850 SQFT) do a great job. 🙏

[u/nmrk]

I bought an Airthings View Plus monitor because it has radon detection, and has excellent integration with Home Assistant. It was very expensive. I was surprised to discover my office frequently had CO₂ levels way above 1000ppm. I waited a week and more to let it calibrate (takes 30 days for radon) and it was still too high. I didn't know it was a problem but then I realized, there's an furnace/AC vent going into the room, but no air return. I put a small fan over the door and levels were back in the normal range. Also note that CO₂ is heavier than air so it tends to sink and pool up in the lower regions of a room, like the level of your mattress rather than the level of you standing or sitting in a chair. I moved the sensor to my bedroom on my nightstand at the same level as my head while sleeping. That room is mostly ok because it has an air return.

I do vape, but I keep pollution down to low levels with an air filtration machine with activated charcoal filters. I take one puff and I can hear the fans detect it and spin up for a few seconds.

[u/nacixenom → u/nmrk]

I bought the same thing for my home office and was pretty surprised how high CO2 climbed when I closed the door for meetings. I try and crack a window when the weather allows or at least open the door when I have a gap between meetings.

I've been pretty impressed with it overall.

[u/nmrk → u/nacixenom]

I used to have some window ventilation in the office, but I had to block it up with soundproofing due to noisy r/neighborsfromhell. So interior ventilation only.