EnviroNearby

Dewey County, Oklahoma air quality history

Daily Air Quality Index summaries from EPA monitors in Dewey, Oklahoma, 2002–2025.

64%
Good days in 2025
46
Median daily AQI, 2025
1
Days above 100 in 2025
364
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Dewey, Oklahoma on 364 days. 232 of those days (64%) were in the Good range, and the median daily AQI was 46. That median is about the same as the typical monitored county in Oklahoma (median 44 across 19 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 210 days. Across the years with fuller monitoring, the share of Good days fell: an average of 80% in 2002–2004 versus 62% in 2023–2025.

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%2002: Good 143 of 166 days2002: Moderate 21 of 166 days2002: Unhealthy for Sensitive Groups 2 of 166 days20022003: Good 264 of 365 days2003: Moderate 87 of 365 days2003: Unhealthy for Sensitive Groups 14 of 365 days2004: Good 301 of 366 days2004: Moderate 64 of 366 days2004: Unhealthy for Sensitive Groups 1 of 366 days20042005: Good 286 of 365 days2005: Moderate 72 of 365 days2005: Unhealthy for Sensitive Groups 6 of 365 days2005: Unhealthy 1 of 365 days2006: Good 245 of 349 days2006: Moderate 92 of 349 days2006: Unhealthy for Sensitive Groups 12 of 349 days20062007: Good 319 of 364 days2007: Moderate 42 of 364 days2007: Unhealthy for Sensitive Groups 3 of 364 days2008: Good 301 of 365 days2008: Moderate 64 of 365 days20082009: Good 211 of 363 days2009: Moderate 151 of 363 days2009: Unhealthy for Sensitive Groups 1 of 363 days2010: Good 252 of 365 days2010: Moderate 111 of 365 days2010: Unhealthy for Sensitive Groups 2 of 365 days20102011: Good 187 of 362 days2011: Moderate 159 of 362 days2011: Unhealthy for Sensitive Groups 16 of 362 days2012: Good 211 of 366 days2012: Moderate 142 of 366 days2012: Unhealthy for Sensitive Groups 13 of 366 days20122013: Good 202 of 365 days2013: Moderate 160 of 365 days2013: Unhealthy for Sensitive Groups 3 of 365 days2014: Good 211 of 361 days2014: Moderate 149 of 361 days2014: Unhealthy for Sensitive Groups 1 of 361 days20142015: Good 256 of 348 days2015: Moderate 92 of 348 days2016: Good 280 of 361 days2016: Moderate 81 of 361 days20162017: Good 262 of 358 days2017: Moderate 94 of 358 days2017: Unhealthy for Sensitive Groups 2 of 358 days2018: Good 212 of 362 days2018: Moderate 143 of 362 days2018: Unhealthy for Sensitive Groups 7 of 362 days20182019: Good 230 of 365 days2019: Moderate 135 of 365 days2020: Good 266 of 365 days2020: Moderate 99 of 365 days20202021: Good 261 of 365 days2021: Moderate 103 of 365 days2021: Unhealthy for Sensitive Groups 1 of 365 days2022: Good 219 of 346 days2022: Moderate 124 of 346 days2022: Unhealthy for Sensitive Groups 3 of 346 days20222023: Good 221 of 365 days2023: Moderate 144 of 365 days2024: Good 221 of 366 days2024: Moderate 139 of 366 days2024: Unhealthy for Sensitive Groups 6 of 366 days20242025: Good 232 of 364 days2025: Moderate 131 of 364 days2025: Unhealthy 1 of 364 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 year0501002002: 90th percentile AQI 642003: 90th percentile AQI 842004: 90th percentile AQI 612005: 90th percentile AQI 742006: 90th percentile AQI 802007: 90th percentile AQI 542008: 90th percentile AQI 612009: 90th percentile AQI 682010: 90th percentile AQI 642011: 90th percentile AQI 842012: 90th percentile AQI 802013: 90th percentile AQI 682014: 90th percentile AQI 672015: 90th percentile AQI 612016: 90th percentile AQI 562017: 90th percentile AQI 642018: 90th percentile AQI 742019: 90th percentile AQI 612020: 90th percentile AQI 612021: 90th percentile AQI 612022: 90th percentile AQI 712023: 90th percentile AQI 712024: 90th percentile AQI 742025: 90th percentile AQI 712002: Median AQI 332003: Median AQI 422004: Median AQI 402005: Median AQI 412006: Median AQI 412007: Median AQI 382008: Median AQI 402009: Median AQI 472010: Median AQI 442011: Median AQI 502012: Median AQI 472013: Median AQI 482014: Median AQI 462015: Median AQI 422016: Median AQI 422017: Median AQI 432018: Median AQI 472019: Median AQI 442020: Median AQI 432021: Median AQI 442022: Median AQI 472023: Median AQI 462024: Median AQI 472025: Median AQI 462002200420062008201020122014201620182020202220242025
  • 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
Ozone21058%
Fine particles (PM2.5)15442%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536423213101004671164Ozone
202436622113960004774112Ozone
202336522114400004671100PM2.5
202234621912430004771129Ozone
202136526110310004461116Ozone
2020365266990000436199PM2.5
20193652301350000446193PM2.5
201836221214370004774115PM2.5
20173582629420004364134Ozone
2016361280810000425687Ozone
2015348256920000426196Ozone
201436121114910004667105PM2.5
201336520216030004868112Ozone
2012366211142130004780136Ozone
2011362187159160005084143Ozone
201036525211120004464112Ozone
200936321115110004768101Ozone
2008365301640000406190Ozone
20073643194230003854115Ozone
200634924592120004180140Ozone
20053652867261004174154Ozone
20043663016410004061105Ozone
200336526487140004284129Ozone
20021661432120003364105Ozone

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 2002–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem