last updated 22 Jan 2022
Model Price Measures Notes
Airthings 2930 wave plus $177 Temp., Humidity (RH), CO2, Radon, VOC, RH,Temp,air presure
Awair Element $149 Temp., Humidity (RH), TVOC, PM2.5, and CO2 levels, tracks over time
Kaiterra Laser Eg $196 Temp., Humidity (RH), TVOC, PM2.5, and CO2 levels, Monitors both indoor and outdoor air quality
Temtop M10 $90 PM2.5, TVOC, formaldehyde (HCHO)
Ecowitt who290 $75

- PM2.5 Particulate Matter < 2.5 µm in diamater. (Combustion particles (smoke), organic compounds, metals)

- Chemicals - TVOCs (Total Volatile Organic Compounds) - VOCs are emitted by a wide array of products numbering in the thousands. Emissions from the use of household spray products, industrial solvents such as trichloroethylene, paint thinner. Concentrations of many VOCs are consistently higher indoors (up to ten times higher) than outdoors.


I tried 2 home AQI monitors Awair and Temtop M10
Comparison of PM2.5 outdoor Awair & Temtop vs other external 
Purple Air  103-152 (Tends to be high)
AirNow      66
Awair       27-78
Temtop      86 - 166

AQAIR


Levels
Other Nomenclature
Good 
Moderate
High
Very High
Very High


Abbreviations:
ppm - Parts per Million
ppb - Parts per Billion
µg/m3 micro grams per cubic meter
CO2


These 5 indexes are aggregated into the Awair Score, a single number ranging from 0 (very unhealthy and uncomfortable air) to 100 (perfectly healthy and comfortable air).
The Awair score, based on a proprietary computation, has a different focus depending on the preference you selected.


AQI Score
80-100 Good
60-80  Fair
0-60   Poor
Causes and Remedies
Examples from my home
Temp RH CO2 TVOC  PM2.5 Score
 71  47 406   81   3    100 
 62  45 520   85   2     92 return after 3 days away
 
 68  41 624   82   1     96 before cooking
 69  43 680  250   7     95 after cooking bkfst
 69  44 731  137   3     95
 
 66 43 458  72 2 100  after windows open at night
 66 44 515 190 8  99  right after cooking 
 66 44 555 356 14 95  1 hr after cooking

 after bathroom cleaning with acetone
 67  44 709  7,500 3     80
 30 min. vent with windows open
 67 42  400   40   5    100   co2 went to min. in outside Air, PM2.5 went up
 1 hr after closing windows which were open at night with N wind
 69 32  450  143   2     91
 
out for 2 days back 45 min.
73 40 624 258 1 94 
 

Temtop M10
Readings in my home:
PM2.5 14-16
TVOC .16-.27
HCHO .04-.05
AQI   54-60
Comparison	Awair	Temtop
I put both monitors outside to compair with external monitors
External Monitors
Airnow       41      43    77
Purple Air  160      152   98
My devices 
Temtop       191 176  194 100
awair         89  77   90  84

Other indoor air quality monitors:
Laser Egg is another air quality monitor
Pressac launch new smart indoor air quality sensor

Reviews:
Best indoor air quality monitors 2022 | TechHive
Spy.com
Performance assessment of low-cost environmental monitors and single sensors under variable indoor air quality and thermal conditions - ScienceDirect

Links:
Heat Index
About TVOC and the Laser Egg+ Chemical
The Standards for Ventilation and Indoor Air Quality