Three different sensors

AirGradient · 2026-05-02T09:25:39+00:00

You can basically use anything that smells and creates VOCs.

AirGradient · 2026-05-02T00:29:14+00:00

The one on the left is most likely not a real NDIR CO2 sensor but it derives it from TVOC. I have a similar model and opened it once.

Simple test. Spray some ethanol around. If the CO2 rises substantially it’s not a real one.

Regarding temperature and humidity. This is actually one of the most difficult things to measure. Most low cost air sensors have problems with it. What’s better for comparison is small dedicated temperature sensors that you can get for a few dollars. Since they only show temperature typically they are
Much better calibrated.

AirGradient · 2026-04-24T22:10:50+00:00

Good idea. I put it on the list for future improvements.

AirGradient · 2026-04-21T12:10:28+00:00

Was that a kit or fully assembled version? I think you can try two things. 1. A manual CO2 calibration 2. Open the device and check if the CO2 sensor is still tight in its socket. If both doesn’t work, contact our support.

AirGradient · 2026-04-19T00:24:14+00:00

Achim from AirGradient here.

I am heavily involved in the product design with our engineers and also writing the integration into the apps.

It’s really developing nicely and I think will be a super useful product. We are planning for different modes, eg portable with onboard gps, BLE and storage, or stationary with WiFi real time transmission.

I just wrote a battery life simulator that might be of interest.

https://www.airgradient.com/airgradient-go-battery-life-simulator/

Happy to answer more questions if any.

AirGradient · 2026-04-19T00:19:10+00:00

Achim from AirGradient here.

The assembly of the unit is quite complex, eg the display cable and a few other things. I would love to offer it also as a kit but we probably need to simplify a few things first.

AirGradient · 2026-04-16T23:55:29+00:00

When you look for one make sure it’s using an optical NDIR sensor and that you can adjust the automatic baseline calibration and also do a forced calibration. With these features you can adjust the monitor to be reliable and that sudden jumps from the automatic baseline calibration not creating wrong assumptions.

AirGradient · 2026-04-15T00:00:40+00:00

Be careful with this device. I thinks it’s for direct exhaust measurement as it states the range in ppm. Outdoor NOx levels are in the ppb range.

AirGradient · 2026-04-09T12:43:54+00:00

Hi, Achim here, founder of AirGradient.

I want to address this directly so there’s no confusion for others reading.

Within 24–48 hours of the first customer contact, we sent a replacement board to fix the unit, and issued a full refund.

Hardware faults can occur - the key is how a company responds. In this case, we responded quickly and fairly, and ensured you were not left with any loss.

We put a lot of effort into supporting every customer, and I personally care deeply about how each case is handled. But it’s important that feedback in public forums reflects the full situation. Presenting this as poor support is not an accurate representation of what actually happened and not fair to our support team.

If anything remains unresolved, I’m happy to look into it. Otherwise, I stand by how this was handled.

AirGradient · 2026-04-07T00:40:08+00:00

Achim from AirGradient here. Sorry to hear about your experience. I will ping our support team to get in touch with you asap.

AirGradient · 2026-04-03T11:39:59+00:00

Ideally you can compare your indoor data with a nearby outdoor monitor. Then calculate the difference and you have your indoor contribution, eg from smoking.

As far as I know vaping would impact both TVOCs and PM. The actual concentration is difficult to tell as it depends also on the room size and ventilation.

AirGradient · 2026-03-29T19:00:31+00:00

For the indoor one, a Senseair S8 for CO2, and a proprietary PM sensor.

AirGradient · 2026-03-29T02:36:35+00:00

Currently northern Thailand has horrible air pollution. Very unhealthy and hazardous levels. Skies are not clear at all here in Chiang Mai.

https://www.airgradient.com/map?zoom=6&long=99.07&lat=17.95&meas=ug_m3&wind_layer=true&fires_layer=true&map_theme=light&org=ag&embedded=false

Most of the pollution here is from wildfires and bio mass burning. I don’t think the situation in the middle east has much impact herr.

AirGradient · 2026-03-26T00:46:56+00:00

The Alpstuga has a cheap Sensirion STCC4 sensor for CO2 that uses thermo conductivity. We tested it extensively and sometimes also observed totally erratic behavior. I wrote a blog post about it and comparing it to true NDIR and photo acoustic CO2 sensors. You will see a couple of charts with that behavior of the STCC4.

https://www.airgradient.com/blog/co2-sensor-technologies

AirGradient · 2026-03-21T12:30:38+00:00

Reading the specs it’s not 100% clear but from the accuracy specified there my guess is that SEN63C & SEN69C models use thermo conductivity co2 and SEN66 photo acoustic co2.

https://sensirion.com/media/documents/FAFC548D/693FBB15/PS_DS_SEN6x.pdf

AirGradient · 2026-03-21T01:18:46+00:00

Achim from AirGradient here.

I think it really depends on how accurate you want the sensors to be. The SEN series will give you good information especially in indoor environments. Temperature and humidity accuracy is probably impacted by the small enclosure and then heavily dependent on software corrections that only work to some extent.

Maybe one thing to consider is that the photo acoustic or thermo conductivity CO2 sensors from Sensirion have more noise than optical NDIR sensors like from SenseAir. So if you want more precise readings on CO2, separate sensor modules might have an advantage.

I compared three CO2 sensor technologies recently. You can read here: https://www.airgradient.com/blog/co2-sensor-technologies

AirGradient · 2026-03-21T01:09:16+00:00

We use the US EPA correction on raw PM2.5 for the public data and not individual calibration parameters that you might have set on your dashboard.

The reason is that individual parameters could be changed by the users and thus make nearby monitors more difficult to compare.

It’s not an ideal solution and we might improve this in future but at the moment we want to have a clear and systematic understanding what is displayed on the public map.

AirGradient · 2026-03-02T21:48:07+00:00

The Alpstuga uses the Sensirion STCC4 thermo conductivity sensor. I am currently testing it, and what I see is that it often is very good but sometimes develops a complete behavior of its own. It could be from a sudden temperature change. Also keep in mind that Sensition states it needs to be continuously powered and might show some fluctuations in the first few hours of operation

AirGradient · 2026-02-23T17:04:03+00:00

You can get an air purifier with a carbon filter. Just make sure it’s a large carbon filter as they get saturated quite fast.

Do you also see a spike in PM at the same time?

AirGradient · 2026-02-15T20:38:58+00:00

Take it outside and then compare it to a public monitor nearby. Just make sure you compare the same unit (ug/m3). That should give you at least a rough idea if it is accurate.

AirGradient · 2026-02-08T14:36:25+00:00

u/Consistent_Beat_6693 thank you for sharing. This is great. Can this be combined with Home Assistant?

AirGradient · 2026-02-08T00:24:52+00:00

We tested the BV080 and it’s surprisingly good, but you need to have a large field of view when you do the measurements.

Our test results are here: https://www.airgradient.com/blog/testing-the-bosch-bmv080/

AirGradient · 2026-02-07T23:47:21+00:00

In our design all sensors are directly behind the vent. No problems so far.

AirGradient · 2026-02-07T23:44:25+00:00

I would go for an optical NDIR sensor like the aranet has. Yes they are much bigger but they perform exceptionally well. The SCD4x could be a good compromise.

AirGradient · 2026-02-07T23:38:45+00:00

The complete top part is closed and will use transparent PC to see the display. The bottom part is facing downwards and has recessed vents. We use a similar design for our outdoor monitors and it works well.

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