EnviroNearby

Bryan County, Oklahoma air quality history

Daily Air Quality Index summaries from EPA monitors in Bryan, Oklahoma, 2013–2018.

85%
Good days in 2018
38
Median daily AQI, 2018
3
Days above 100 in 2018
301
Days with an AQI in 2018 (of 365)

In 2018, EPA reported a daily Air Quality Index (AQI) for Bryan, Oklahoma on 301 days. 257 of those days (85%) were in the Good range, and the median daily AQI was 38. That median is lower than the typical monitored county in Oklahoma (median 42 across 23 counties), and lower than the typical monitored U.S. county (41). The main pollutant was ozone on 301 days.

The most recent year with data for this county is 2018; EPA's files for 2019–2025 contain no row for it, which usually means its monitors stopped reporting.

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%2013: Good 113 of 137 days2013: Moderate 22 of 137 days2013: Unhealthy for Sensitive Groups 2 of 137 days20132014: Good 293 of 333 days2014: Moderate 38 of 333 days2014: Unhealthy for Sensitive Groups 2 of 333 days20142017: Good 262 of 294 days2017: Moderate 32 of 294 days20172018: Good 257 of 301 days2018: Moderate 41 of 301 days2018: Unhealthy for Sensitive Groups 3 of 301 days2018
  • 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 year0501002013: 90th percentile AQI 712014: 90th percentile AQI 512017: 90th percentile AQI 512018: 90th percentile AQI 582013: Median AQI 352014: Median AQI 392017: Median AQI 392018: Median AQI 382013201420172018
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2018

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
Ozone301100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20183012574130003858119Ozone
2017294262320000395193Ozone
20143332933820003951126Ozone
20131371132220003571126Ozone

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.

All monitored counties in Oklahoma

Source: U.S. EPA AirData, “Annual AQI by County” files for 2013–2018 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem