What is the air quality trend in Herndon?

Over the past 3 days, Herndon had an average AQI of 24 based on station measurements. The worst day was 2026-10-21 with AQI 27.

How is Herndon air quality measured?

Air quality in Herndon is measured by ground-level monitoring stations that report PM2.5 and PM10 concentrations hourly. CERNS.IO aggregates readings from nearby stations and converts PM2.5 to the US EPA Air Quality Index (AQI) scale.

Air Quality History for Herndon, United States

Name: Herndon Air Quality History
Creator: CERNS.IO
License: https://creativecommons.org/licenses/by/4.0/

Historical PM2.5 and AQI trend from monitoring stations near Herndon, United States.

142

Current AQI
Unhealthy for sensitive groups Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

45h

PM2.5 Station

45h · 20 stations

Temperature GFS model

8pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	Hours	Stations
2026-10-21	27	23–34	6.6 µg/m³	3h	21
2026-10-20	23	19–29	5.5 µg/m³	24h	20
2026-10-19	24	17–30	5.7 µg/m³	18h	23

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