What is the air quality trend in Diamond Bar?

Over the past 3 days, Diamond Bar had an average AQI of 33 based on station measurements. The worst day was 2026-09-03 with AQI 37.

How is Diamond Bar air quality measured?

Air quality in Diamond Bar 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 Diamond Bar, United States

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

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

Current AQI
Good Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

45h

PM2.5 Station

45h · 108 stations

Temperature GFS model

8pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	PM10 avg	Hours	Stations
2026-09-05	33	29–42	7.8 µg/m³	4.9	16h	109
2026-09-04	30	24–35	7.1 µg/m³	3.6	24h	109
2026-09-03	37	28–54	9.0 µg/m³	3.7	5h	108

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