How clean is the air around Eureka?
EPA monitor data for the county that contains Eureka, CA: how many days each year rated good, moderate or unhealthy on the Air Quality Index, and how that has changed.
U.S. Environmental Protection Agency, AirData annual AQI summaries by county.
This story was assembled using AI and public data sources.
0 days of unhealthy air in Humboldt County in 2025.
Good air days in 2025: 285 of 365 — 78.1% of monitored days rated good
Share of days rated "good"
- 2010: 95.3
- 2011: 75.9
- 2012: 68.9
- 2013: 61.9
- 2014: 41.6
- 2015: 66
- 2016: 78.7
- 2017: 81.6
- 2018: 82.5
- 2019: 93.7
- 2020: 86.9
- 2021: 91.2
- 2022: 93.2
- 2023: 77.8
- 2024: 72.7
- 2025: 78.1
Days above the moderate range (unhealthy for at least sensitive groups)
- 2010: 0
- 2011: 0
- 2012: 0
- 2013: 1
- 2014: 6
- 2015: 0
- 2016: 0
- 2017: 8
- 2018: 6
- 2019: 0
- 2020: 4
- 2021: 0
- 2022: 0
- 2023: 11
- 2024: 0
- 2025: 0
Median AQI
- 2010: 30
- 2011: 38
- 2012: 39
- 2013: 44
- 2014: 53
- 2015: 40
- 2016: 38
- 2017: 37
- 2018: 35
- 2019: 28
- 2020: 29
- 2021: 29
- 2022: 24
- 2023: 32
- 2024: 38
- 2025: 38
2025 air days by category
- Good: 285
- Moderate: 80
What it means
Good-air days are down about 17 percentage points since 2010.
The worst stretch in this window was 2023, with 11 days above the moderate range and a peak AQI of 299.
AQI days are only counted where the EPA has monitors, so counties with fewer monitors report fewer measured days.
Sources
- U.S. Census Bureau — American Community Survey (ACS) 5-year estimates — Population, income, housing, education, commuting and poverty figures
- Census Bureau API — ACS Detailed Tables — The endpoint these pages are generated from
- data.census.gov — Look up the same tables for any place yourself
- ACS accuracy statement — Estimates carry margins of error; small places vary the most
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