What is the air quality trend in Castro Valley?

Over the past 7 days, Castro Valley had an average AQI of 27 based on station measurements. The worst day was 2026-10-18 with AQI 34.

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

165h

PM2.5 Station

165h · 103 stations

Temperature GFS model

28pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	PM10 avg	Hours	Stations
2026-10-20	21	16–52	5.0 µg/m³	5.4	23h	91
2026-10-19	23	20–28	5.4 µg/m³	11.7	24h	103
2026-10-18	34	24–41	8.3 µg/m³	20.3	24h	96
2026-10-17	30	24–35	7.2 µg/m³	12.8	24h	106
2026-10-16	31	23–36	7.4 µg/m³	12.3	24h	102
2026-10-15	27	24–35	6.6 µg/m³	12.3	24h	109
2026-10-14	25	22–30	5.9 µg/m³	11.7	22h	109

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