What is the air quality trend in Castro Valley?

Over the past 3 days, Castro Valley had an average AQI of 25 based on station measurements. The worst day was 2026-07-21 with AQI 30.

How is Castro Valley air quality measured?

Air quality in Castro Valley 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 Castro Valley, United States

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

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

Current AQI
Good Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

46h

PM2.5 Station

46h · 107 stations

Temperature GFS model

8pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	PM10 avg	Hours	Stations
2026-07-22	22	21–23	5.2 µg/m³	1.1	3h	110
2026-07-21	30	24–58	7.4 µg/m³	4.9	24h	106
2026-07-20	23	17–60	5.5 µg/m³	3.2	19h	103

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