I mostly use mine just for monitoring humidity (I use a humidifier, but don’t want the humidity going up past 60% or bad things can start to grow) and CO2 which I try to keep below 800-ish PPM by keeping the window slightly open (except during pollen season, which is now)

There was an initial effort of doing things and seeing the effects and eventually finding a nice equilibrium. I now have a feel for what’s needed and it’s not something I put any thought into. I basically check it when the seasons change. Rather than contributing to anxiety, I am now relieved of unknowns.

I’m quite allergic to pollen, and very sensitive to things like smoke, so I’ve already someone more focused on managing my environment than a normal person. A wick based humidifier (don’t use ultrasonic, those breed bacteria and launch them into the air) and large air filter with a big but quiet fan are the most important things in my room. Yes, even the bed.

These devices can also be a good way to catch localized air pollution that exceeds safety limits, though where I live that’s not an issue. Citizens capable of checking air and water quality is a positive in my opinion.

Not the OP, but my airgradients are part of my home assistant setup. They measure the temperature and humidity, and the values are used for controlling the radiators and the humidifiers. Whenever the co2 or ppm count is too high, I flash some leds red to remind whoever is in the room to open a window - which is extremely important because a lot of people don’t have a natural reflex for getting fresh air. This is especially important when we have guests over, in our small living room, the air goes bad fast.

I was able to improve my sleep because I found out that my waking up in the night was correlated with high co2 values. Same thing with performance in my home office. It’s a small room and the reminder to open a window while I’m in the flow is just amazing.

But: my airgradient devices were anything but “rock solid“. Constant reboots, hung ESPs, I had to swap out the senseair sensors because apparently they go bad, etc.

I'm also an AirGradient user. AirGradient prioritizes accuracy and it's fully OSS. The sensors are fully replaceable; not if but when they eventually lose accuracy. I'd argue that monitoring PM2.5 levels indoors is even more crucial than outdoors. In our home, we have good air recirculation and HEPA filters in every room. Since we began keeping indoor air clean, our spring allergies (and general allergy issues throughout the year) have become much less severe. IMO AirGradient is the best way verify current levels and ultimately ensure the filtration works. https://imgur.com/a/UIkkANL

Not a fan of my own medical example there. If I knew my kid was going to be blind, there are lots of actions I would take: Educating myself, potentially preparing the home environment etc.

During wildfire season (which was never a thing for most the USA, but now is thanks to Canadian wildfires and climate change), it's really helpful to get instant particle counts indoors and outdoors. Indoors, you can mitigate with "circulation" mode on your hvac system (to filter through the furnace fitler), or by running air purifiers. Outdoors you can just avoid exposure by coming inside / avoiding trips.

I´m living in the middle of a city, and PM2.5 levels get very high at times. We are way above the yearly 5ug/m3 recommendation. So I just bought a lot of air purifiers (just HEPA, everything else commercially available is useless) and they get switched on if the levels get high (via HomeAssistant). I have a device in the garden and another inside, so I am monitoring the difference on a regular basis. I optimize (manually, no fancy data crunching) for low noise produced by the filters and low <2-3ug/m3 PM2.5 values indoors. I don´t have forced ventilation, so I need to know how much do I open the windows to get humidity and VOCs down, while not letting in too much smog. Sounds more complicated than it really is.

If you live in a part of the country where wildfire smoke is common, you can use a PM2.5 sensor (which airgradient has -- and air lab does not) to determine if you're effectively keeping the smoke out of your home and can help you determine whether or not to eg use air purifiers.

Among the probably most important and universally relevant measurements offered by air quality monitors is carbon dioxide/monoxide. Humans are not really built for realising when these are elevated, other than feeling sleepy and generally experiencing reduced mental capacity, which by its self-referential nature is not conducive to understanding that you are experiencing reduced mental capacity or being motivated to take measures about it (such as opening windows).

These are all of the ways in which air monitoring information is actionable for me:

— Excessive carbon dioxide: as mentioned, it’s a call to open windows and possibly doors, depending on wind direction and window/door configuration in the flat and the building. It can reach surprising, and in my case unsafe by at least one country’s standards, levels overnight if your flat has decent insulation and little airflow. Besides, it just feels nice to have more oxygen knocking about your internals.

— Excessive (which should really mean non-zero, but in today’s ecology let’s say “elevated”) PM2.5 means I should close windows (usually this pollution comes from outside) and ramp up air filtering, and potentially postpone exercise while particulate matter is too high. I have a separate cheap air filter but lately it turned out that a Mitsubishi dehumidifier does a great job at this—which, by the way, I have realized only thanks to an air monitor.

— If both carbon dioxide and particulate matter are high, I’d most likely open the windows first to lower the former then close the windows and run air filtering while hanging out at the office or having a walk (potentially with an N95 mask on if it’s really bad outside).

— VOC, which often originate from chemicals used in furniture or flooring, if your monitor measures those, could probably be addressed by adding activated carbon layer to your air filter (and by opening windows). I think they are filtered slowly and this might take months, but my monitor did not measure VOCs so I don’t have first-hand experience. An air quality monitor could help you understand whether you are wrong or right in thinking your new floor made your air full of VOCs when all you can go by otherwise is just a vague chemical smell.

— Elevated background radiation means you should probably just move, usually it is building materials or something not easily removable anyway.

I would say that with these numbers available there is a danger you’d stress over and min/max them. It’s probably better to just use the measurements to understand the patterns and see if something is really out of ordinary or elevated for prolonged periods of time. I did that first (and did not expect to see how quickly carbon dioxide builds up, how quickly everything deteriorates with any cooking, including when done by a neighbour if I open windows and the wind blows the wrong way, the speed with which outside pollution permeates the indoor space, how effective my air filtering is, etc.), now my air monitor is broken and I am not overly concerned until I have to move to a new place.