My concise list is very short. I do agree PM2.5 and PM10 are the two major particles to look out for.
I only buy air quality meters that:
A. List the sensors inside the unit
AND
B. The sensor checks out as useful while I am wearing my critical/cynical bifocals.
I do not think a curious individual needs to spend the money on a Dylos 1100. If your homeowner's insurance is denying a claim because you bought your sensor on Amazon, sure, think about a Dylos. I have two of them sitting on a shelf that I am willing to part with for less than I paid, plus shipping from Alaska. I have one with data logging, the other without.
I have a fair amount of respect for the Plantower S-50 series particle counters. That is an actual google-able sensor that goes inside a finished particle counter. Besides a sensor, a finished particle counter needs a display, a power supply, and a small bit of processing power to convert bitstream from the sensor to pixels on the display. If you have a Raspberry or an Arduino already you can buy a bare Plantower S50 to hang off it, and find software to match your display on a microcomputer forum in about 0.0034 seconds. Just wire it up, load up the sketch and watch the display.
In fairness, besides passing the critical/ cynical bifocal inspection, I have run 4 of the Plantower S50s side by side with my pair of Dylos'. I find the Plantower S50 tracks within 1-2% of a Dylos for PM2.5 counts between 6 and 200 mcg/m3. Less than 6 mcg/m3 is excellent AQ. Above 200 mcg/m3 you should be able to tell you have an AQ issue just from your nose and your eyes. FWIW mine are all Plantower model PM
S5003. There are several members in the S50 family.
All of the smoke detectors in my home are dual equipped with 'smoke' and 'carbon monoxide' detection circuits. The 'smoke' circuit is a fairly unsophisticated particle counter. When it detects enough particles in the air, it alarms. The 'carbon monoxide' circuits, first generation, actually used a sensor that measured the amount of oxygen in the air. When oxygen dropped, the circuit ass-u-me-d CO or CO2 was increasing, and alarmed. New production smoke/CO detectors, I don't care what sensor they are using. These devices save lives.
Besides PM2.5 and PM10, I find the NDIR technology for CO2 (
https://en.wikipedia.org/wiki/Nondispersive_infrared_sensor ) passes the critical/cynical bifocal test.
If you want to measure your CO2 levels in the house, especially in a tightly built home, there is a handful of NDIR CO2 sensors out there. If you know what sensor the mfr put in the product you can read up on the sensor and make up your own mind. If the mfr is not telling you what CO2 sensor is inside the product, just selling you NDIR tech without telling you which sensor, I wouldn't buy it. Wouldn't even consider it.
As of today, January 2024, there is no consumer grade/price VOC or formaldehyde sensor that passes my critical/cynical bifocals. There is some promising tech out there, but repeatability, calibration, is a hurdle not yet cleared. If you really need to measure your VOCs I think you need to leave a credit card in the safe at your local "Fire and Safety" store to rent a sensor/ data logger combo in the $3k to $5k range for $50-100 per day. I trust the PID (photoionization detection) and TDL (tunable diode laser) sensors, if the calibration certificate is current and the unit is not physically damaged.
If you have a product next to your baby's crib today, it cost less than US$2000, and is displaying "VOC" as a value, I am 100% confident the unit is actually monitoring the presence or absence of some gas other than formaldehyde or methane, and making assumptions on a lookup table somewhere in the software that may or may not be correct for your situation.
@Ovationcs257 , the "VOC" graph above looks to me like it could very well be CO2, esp if the ERV kicks on at 0200. My first step in your shoes would be to choose a product with a known NDIR sensor for CO2 and see how well the CO2 counts track with the displayed VOC graph. In 900sqft I have to run my HRV 40 minutes per hour on low when it is just me here, when the wife is home I have to run the HRV on medium/continuous to keep the CO2 levels down in the green zone.
As far as the 'acrylic box from Amazon' (very fair, BTW) there is no one consistent vendor. I think this started out as lone 14 year old on the back porch with one microcomputer. Once he had his code working, he built ten of them. Might be a girl, no offense. Sold ten in like 4 minutes. Bought a small wave solder pond, built 20 more. Had to hire a sibling to populate the bare PCBs. Hired another sibling to make the very simple cases. Kept selling product. Probably has a few k sqft under lease now for the factory. The fastest way to find the product on the big river website tonight was to search on "Plantower Air Quality", click on the acrylic box, and then select the other product with the CO2 detector on it. I do notice the current text does not include "SensAirS8" as the CO2 detector, but the possibly out of date pictures still show a SensAirS8 sensor mounted. This is a google-able sensor device, and the big river's return policy is pretty good. The temp/RH sensors on these devices are not very fabulous; but for the price, I don't care.
Good luck and best wishes.
