I have a question about calibration, have you tried measuring the CO2 sensor and PM sensor against a known calibrated sensor?

They will always give a useful 'relative change' indication but how does the SenseAir and the Plantower sensors compare with more expensive measurement equipment?

Thank you for this. As someone who lived through the hellish airscape of last year's Australian bushfires, and spent quite a bit of time discussing, advising, and publicizing air quality concerns, efforts like this are sorely needed.

At this point I've been recommending people buy PurpleAir monitors for grassroots air quality monitoring, but this looks like a really great DIY option.

I'm particularly excited about the CO2 sensor, since until this point I've been focused mostly on PM2.5 and PM10 particles, but am really keen to figure out if my stuffy apartment bedroom (and baby's room) is reaching too high CO2 levels at night (with corresponding headaches and impact on cognitive performance).

Yes, often when you seal your house to keep PM2.5 low, your CO2 values go up.

We measures this in classrooms [1] and I also wrote about the benefits of positive pressure systems to have near zero PM2.5 and low CO2 at the same time [2] even on heavily polluted days.

[1] https://www.airgradient.com/resources/we-measured-the-co2-le...

[2] https://www.airgradient.com/resources/positive-pressure-syst...

Are the CO2 levels mentioned in [2] above from an air conditioned room? This detail is not mentioned in the article. I am trying to understand if air exchange provided by the air conditioner makes any difference on reducing CO2 levels in the room.

being largely human-made and relatively recently created, pm (particulate matter) and voc’s (volatile organic compounds), and perhaps rarer (but potent) pollutants like ozone, carbon monoxide, and radon, are important to monitor for health. note that co2, while fashionable to be concerned about these days, is not a significant health concern (life evolved in relatively significant concentrations of co2) beyond suffocations at extremely high concentrations.

Are you able to share the AirGradient business model, which allows the company to support publication of open-source docs, software and hardware for DIY air sensors?

The guide is much appreciated!

We are based in Northern Thailand which is impacted by seasonal wildfires with very high levels of PM2.5.

AirGradient originally developed out of our desire to help our school to manage the air quality during this time of the year more effectively and to ensure that our kids breathe healthy air inside the classroom.

Most of the benefits come from our cloud platform that analyses the air quality data sent from the sensors and provides real time alerts and communication to the relevant staff (e.g. PE teachers when air quality gets worse).

It has also some unique features like integration of the school air quality policy. More information is on our website [1].

This service comes with our professional air quality monitor which has additional hardware components to achieve a very high degree of reliability.

We provide the open source version due to a desire to empower as many people as possible to measure the air quality in their environment and thus reduce their health risks due to bad air.

It also helps us to get customers onto our air monitoring platform in countries where our sensor is not available yet. A day care center in California for example build 12 DIY sensors and connected them to our platform to measure the indoor air quality in its classrooms.

Currently we have a strong focus on schools and if anyone of you has a connection to a school and is interested to learn more about how our platform could help, please get in touch with me.

[1] https://www.airgradient.com/schools/

Very cool that this got posted today! I am visiting Chiang Mai this week from the province of Phichit where I teach English. I sent you an email at the support address.

Can you share any thoughts on a similar DIY project for outdoor air monitoring?

I.e. is it feasible to make something battery powered and connected to an indoor base station or gateway via some low power radio link (bluetooth low-energy? z-wave?). Would these same sensors work outdoors or quickly fail due to harsh environment?

How complex would it be to make a housing that is sufficiently weather proof yet coupled to the environment to read ambient environmental conditions? I can imagine sun exposure, wind, high dust loads, rain, and condensing humidity all being very challenging for a DIY device to stick out in a yard or balcony.

Serious question: what happens to air quality while I’m soldering all of those components? I have always wondered how toxic solder and flux fumes are.

When I solder, PM2.5 goes into very unhealthy territory. There are solder smoke absorbers with carbon filters that I would recommend to use.

Any solder smoke absorber recommendations? I’ve never heard of those.

I bought the Aven 17701 recently, it seems to do the job. It's just a fan with an activated carbon filter.

Yeah just do it outside if possible with a makeshift work bench

That's fine this time of year but not in winter.

Breathing in fumes is never healthy. That's why you have filters that suck the solder fumes away.

How would you say this fares against a kaiterra or tongdy machine for example? With diy projects, I'm always concerned about managing temperature and humidity impact on readings, especially on sensors like the plantower. I've had issues in the past with monitors in very humid environments like Thailand and Singapore.

Disclaimer: I also run an environment data platform business

Amazing work, and I love how you have a focus on schools. My son's old school was adjacent to a major thoroughfare here in Melbourne, Victoria, and it was the biggest negative with it for me. Only for a year, but I'm hopeful too much damage wasn't done.

Would love a full package sensor like this for our own house (I have three purifiers..) so I'll get in touch once I've learned soldering, which requires acquiring the necessary tools.

How does this project compare to luftdaten? Have you considered if the projects could share data?

https://sensor.community/en/sensors/airrohr/

Hey there, I sent a contact on the site but I didn't get any response. Same username @ a common email provider. Would love a free PCB if possible! No worries if you've run out or anything, of course. :)

Just FYI for others, I also sent a contact on the site last time around, but I actually did get a response. It took maybe a week or so, but they're probably very busy!

I got your message. Will reply to all messages later tonight.

no worries! Cheers :)

I might take you up on this offer, where are you sending from?

We are based in Thailand. Normally it takes around 3 weeks to arrive.