Previous posts for the EPA PM 2.5 show these breakpoints:
Good 0 - 50 | 0.0 – 12.0
Moderate 51 - 100 | 12.1 – 35.4
Unhealthy for Sensitive Groups 101 – 150 | 35.5 – 55.4
Unhealthy 151 – 200 | 55.5 – 150.4
Very Unhealthy 201 – 300 | 150.5 – 250.4
Hazardous 301 – 400 | 250.5 – 350.4
Hazardous 401 – 500 | 350.5 – 500.4
And reference AQI Breakpoints | Air Quality System | US EPA as the source. AQI Breakpoints | Air Quality System | US EPA
That page now seems to have the breakpoints at (raw values) 0 - 9.0, 9.1 - 35.4, 35.5 - 55.4, etc. However, the EPA page only shows breakpoints for “24 HOUR” and “24-HR BLK AVG” (whatever that is).
I am using the posted (old?) ‘pm2.5’ sensor value for my calculations, and mine are little lower than the Purple Air PM2.5 map.
Have the breakpoints changed recently?