I made my Air Monitor with 3D printing in mind.

Because I do use ABS and ASA monitoring, Formaldehyde seems a must.

Some code is sensor-specific but easily changed

With "reboot_timeout: 0s" ,( no "s ) in both the api: and wifi: sections, it will stop rebooting and work in both stand-alone and logging modes

My sensors used:

• SHT-40 Temperature and Humidity

• SGP-30 CO2 and VOC

• PMS5003S Particles 1, 2.5, 10 ug/m3 AND CH2O(Formaldehyde)

• ZE08-ch2o Formaldehyde

PMS5003S and ZE08-CH2O read Formaldehyde slightly differently.     PMS5003S is known for cross-sensitivity to some VOCs, such as alcohol, acetone, and acetaldehyde...SO the ZE08-HC2O makes a perfect relative comparison.

If you want, I added code for 1 WS2812 addressable LED on ALED pins to "Breathe" when any measured levels are exceeded.

• If all sensors are in the normal range, the LED is off.

• If any sensor changes threshold levels and "Beathe" in the color of the highest threshold level.

• ie: Off. Yellow, Orange, Red, Purple

DO NOTE: If it turns PURPLE, you should likely vent the room and get out.

I borrowed changes in the top button operation and changed some button timing.

https://www.printables.com/model/1436008-3d-printer-emission-sensor-array-sensorbox-v2-code

• Fast Press, 1 - 800mS dims the display by increments and resets alarms for 3 minutes, when on.

• Long Press, 850 - 2200mS Changes Display Pages (4), Main, 1h and 24h graphs, and WiFi Connect pages

• Very Long, 2400 - 6000mS Save SGP30 baseline

• Ultra Long 6000 - 10,000mS Enable/Disable WiFi

I added a speaker on GPIO17 with onboot, and alarms as in some Professional Units, if level 3 chirp warning and siren if level 4

Both warnings have a 3-minute reset with a fast tap of the top button.

I also added the ability for a temporary button on GPIO40 to test the alarms for debugging (courtesy of Google Gemini).   Connect the button from GPIO40 to GND.   1st press repeating CHIRP,  2nd press - SIREN,  3rd press off.

The clock is Internet NTC and currently set for Denver; you will likely need to look up your TimeZone code to change it.

• change line 105, timezone: "MST7MDT,M3.2.0/2:00,M11.1.0/2:00" #Denver with DST and DST rules

      ref MST7MDT = MST=MountainStandardTime, 7 = -7 tz, MDT= MountainDaylightTime

           M3.2.0/2:00; Month 3, week 2, 0 first day of week/2:00 am

            M11.1.0/2:00; Month 11, week 1, 0 first day of week/2:00 am

NOTE: I used the Proleptic Format to add Daylight Saving Time rules

The NTC timezone spec is in TZ_rules.txt if needed.

As in all my posts, the SketchUp CAD files(SKP) are included