EnviroNearby

Sequoyah County, Oklahoma air quality history

Daily Air Quality Index summaries from EPA monitors in Sequoyah, Oklahoma, 2004–2025.

72%
Good days in 2025
42
Median daily AQI, 2025
2
Days above 100 in 2025
359
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Sequoyah, Oklahoma on 359 days. 258 of those days (72%) were in the Good range, and the median daily AQI was 42. That median is about the same as the typical monitored county in Oklahoma (median 44 across 19 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 224 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 69% in 2006–2008 versus 68% in 2023–2025.

Years with fewer than 120 monitored days (2004, 2005) are shown in the table but left out of comparisons and trend statements.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Share of monitored days in each AQI category, by year0%25%50%75%100%2004: Good 18 of 35 days2004: Moderate 17 of 35 days20042005: Good 31 of 108 days2005: Moderate 74 of 108 days2005: Unhealthy for Sensitive Groups 3 of 108 days2006: Good 176 of 309 days2006: Moderate 119 of 309 days2006: Unhealthy for Sensitive Groups 14 of 309 days20062007: Good 255 of 365 days2007: Moderate 107 of 365 days2007: Unhealthy for Sensitive Groups 3 of 365 days2008: Good 293 of 365 days2008: Moderate 72 of 365 days20082009: Good 284 of 344 days2009: Moderate 60 of 344 days2010: Good 220 of 281 days2010: Moderate 60 of 281 days2010: Unhealthy for Sensitive Groups 1 of 281 days20102011: Good 232 of 361 days2011: Moderate 121 of 361 days2011: Unhealthy for Sensitive Groups 8 of 361 days2012: Good 237 of 363 days2012: Moderate 110 of 363 days2012: Unhealthy for Sensitive Groups 14 of 363 days2012: Unhealthy 2 of 363 days20122013: Good 276 of 365 days2013: Moderate 88 of 365 days2013: Unhealthy for Sensitive Groups 1 of 365 days2014: Good 277 of 353 days2014: Moderate 76 of 353 days20142015: Good 304 of 365 days2015: Moderate 61 of 365 days2016: Good 303 of 361 days2016: Moderate 58 of 361 days20162017: Good 298 of 358 days2017: Moderate 60 of 358 days2018: Good 259 of 363 days2018: Moderate 104 of 363 days20182019: Good 279 of 361 days2019: Moderate 82 of 361 days2020: Good 304 of 362 days2020: Moderate 57 of 362 days2020: Unhealthy for Sensitive Groups 1 of 362 days20202021: Good 250 of 360 days2021: Moderate 108 of 360 days2021: Unhealthy for Sensitive Groups 2 of 360 days2022: Good 278 of 364 days2022: Moderate 84 of 364 days2022: Unhealthy for Sensitive Groups 2 of 364 days20222023: Good 227 of 365 days2023: Moderate 138 of 365 days2024: Good 252 of 366 days2024: Moderate 114 of 366 days20242025: Good 258 of 359 days2025: Moderate 99 of 359 days2025: Unhealthy for Sensitive Groups 2 of 359 days2025
  • Good
  • Moderate
  • Unhealthy for Sensitive Groups
  • Unhealthy
  • Very Unhealthy
  • Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median and 90th-percentile daily AQI, by year0501002004: 90th percentile AQI 612005: 90th percentile AQI 792006: 90th percentile AQI 902007: 90th percentile AQI 692008: 90th percentile AQI 612009: 90th percentile AQI 582010: 90th percentile AQI 672011: 90th percentile AQI 732012: 90th percentile AQI 772013: 90th percentile AQI 622014: 90th percentile AQI 592015: 90th percentile AQI 552016: 90th percentile AQI 532017: 90th percentile AQI 542018: 90th percentile AQI 592019: 90th percentile AQI 562020: 90th percentile AQI 542021: 90th percentile AQI 592022: 90th percentile AQI 582023: 90th percentile AQI 622024: 90th percentile AQI 592025: 90th percentile AQI 572004: Median AQI 492005: Median AQI 582006: Median AQI 482007: Median AQI 402008: Median AQI 372009: Median AQI 372010: Median AQI 382011: Median AQI 442012: Median AQI 442013: Median AQI 392014: Median AQI 382015: Median AQI 362016: Median AQI 382017: Median AQI 382018: Median AQI 412019: Median AQI 412020: Median AQI 372021: Median AQI 412022: Median AQI 422023: Median AQI 462024: Median AQI 442025: Median AQI 42200420062008201020122014201620182020202220242025
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2025

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

PollutantDays as main pollutantShare of monitored days
Fine particles (PM2.5)22462%
Ozone13538%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253592589920004257138PM2.5
20243662521140000445997PM2.5
20233652271380000466284PM2.5
20223642788420004258122PM2.5
202136025010820004159122PM2.5
20203623045710003754141PM2.5
2019361279820000415667PM2.5
20183632591040000415990PM2.5
2017358298600000385474Ozone
2016361303580000385374Ozone
2015365304610000365593Ozone
2014353277760000385990Ozone
20133652768810003962105Ozone
2012363237110142004477156Ozone
201136123212180004473119Ozone
20102812206010003867129Ozone
2009344284600000375893Ozone
2008365293720000376193Ozone
200736525510730004069122Ozone
2006309176119140004890140Ozone
2005108317430005879115PM2.5
20043518170000496177PM2.5

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

Counties in Oklahoma with a similar median AQI in 2025

All monitored counties in Oklahoma

Source: U.S. EPA AirData, “Annual AQI by County” files for 2004–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem