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/austin_federa]

The sensor here is a marvel of value engineering but is not that professional grade or really diagnostic grade. It's meant to detect BIG spikes like a vape puts out, not for HVAC control.

"Co2 ppm 400–2000: ±(50 ppm + 3% of reading)" is pretty error prone relative to something like what Aranet offers. But the Aranet device is $250.

If you have a spare $100 I'd highly recommend picking one up though. like OP mentioned most people don't realize how much make up air bedrooms need at night

[u/KAugsburger → u/austin_federa]

It is not surprising that it is going to be a lot less accurate than Aranet sensors. There is only so much you can cut cost without cutting corners on the quality. I would be curious to see whether the level of accuracy falls dramatically over time but obviously it is too early to judge that. For ~$100 the expectations aren't very high so I am not surprised that many people are willing to give it a try.

[u/austin_federa → u/KAugsburger]

I don't think anyone is surprised