+Air Quality Index (AQI) Measurement
Don's Home Health | Air Quality Index (AQI) Measurement
last updated 28 Aug 2021
Data Sources - Reports:
California Air Quality Index (AQI) | IqAir
N. Central California | PurpleAir.com | Davis | Homewood
Check the Air Quality in Davis, California - BreezoMeter

With Forecast:
AirNow.gov is a partnership of the EPA, NOAA and several other agencies to provide AQI information
Accuweather 

Sensors:
Accuweather Plume Labs
AirNow (EPA)
The AirNow site displays hourly, not real-time, readings. 
Fire and Smoke Map EPA

Purple Air 
 The data comes from the commercial sensors the company sells,
 which members of the public install on porches, yards and
 other neighborhood sites.  
Sensors are less accurate than AirNow
You can click on "standard" in the box at the bottom
to get a conversion to match other AQI systems.
Discrepencies in reports:
From PurpleAir to AirNow, Your Air Quality Maps for Wildfire Smoke | KQED
Users have noticed a discrepancy between what official sites are reporting and the readings displayed on PurpleAir.

Using AirNow During Wildfires Web Cams:
Westshore Cafe
Fire Camera Displays | Nevada Seismological Lab

Examples:
Date Location AirNow Purple
Air IqAir 
E.g. on August 23 2021 AQI at Tahoe City was reported as:
 Purple Air - 770-957
 AirNow (EPA)- 566
 AccuWeather - 138

Examples Aug 23: 







View from West Shore Cafe web cam

View from our cabin at Homewood
More examples:
AirNow Aug 29, 2021:

Location of sensors at Lake Tahoe
Sacramento

See:
Californians Turn to Low-Cost Sensors for Highly Local Air Quality Data | KQED