EnviroNearby

Loudon County, Tennessee air quality history

Daily Air Quality Index summaries from EPA monitors in Loudon, Tennessee, 1990–2025.

85%
Good days in 2025
39
Median daily AQI, 2025
0
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Loudon, Tennessee on 365 days. 312 of those days (85%) were in the Good range, and the median daily AQI was 39. That median is about the same as the typical monitored county in Tennessee (median 39 across 23 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 199 days. Across the years with fuller monitoring, the share of Good days rose: an average of 49% in 1996–2005 versus 79% in 2023–2025.

Years with fewer than 120 monitored days (1990, 1991, 1995, 1997, 2003) 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%1990: Good 24 of 25 days1990: Moderate 1 of 25 days19901991: Good 36 of 36 days1995: Good 61 of 61 days19951996: Good 238 of 366 days1996: Moderate 90 of 366 days1996: Unhealthy for Sensitive Groups 30 of 366 days1996: Unhealthy 8 of 366 days1997: Good 33 of 34 days1997: Moderate 1 of 34 days19972003: Good 10 of 47 days2003: Moderate 37 of 47 days2004: Good 128 of 278 days2004: Moderate 137 of 278 days2004: Unhealthy for Sensitive Groups 12 of 278 days2004: Unhealthy 1 of 278 days20042005: Good 100 of 282 days2005: Moderate 136 of 282 days2005: Unhealthy for Sensitive Groups 45 of 282 days2005: Unhealthy 1 of 282 days2006: Good 116 of 275 days2006: Moderate 132 of 275 days2006: Unhealthy for Sensitive Groups 25 of 275 days2006: Unhealthy 2 of 275 days20062007: Good 83 of 279 days2007: Moderate 154 of 279 days2007: Unhealthy for Sensitive Groups 35 of 279 days2007: Unhealthy 7 of 279 days2008: Good 133 of 244 days2008: Moderate 96 of 244 days2008: Unhealthy for Sensitive Groups 15 of 244 days20082009: Good 203 of 240 days2009: Moderate 36 of 240 days2009: Unhealthy for Sensitive Groups 1 of 240 days2010: Good 157 of 237 days2010: Moderate 72 of 237 days2010: Unhealthy for Sensitive Groups 8 of 237 days20102011: Good 164 of 245 days2011: Moderate 70 of 245 days2011: Unhealthy for Sensitive Groups 11 of 245 days2012: Good 171 of 243 days2012: Moderate 59 of 243 days2012: Unhealthy for Sensitive Groups 11 of 243 days2012: Unhealthy 2 of 243 days20122013: Good 209 of 281 days2013: Moderate 72 of 281 days2014: Good 184 of 278 days2014: Moderate 92 of 278 days2014: Unhealthy for Sensitive Groups 2 of 278 days20142015: Good 185 of 276 days2015: Moderate 91 of 276 days2016: Good 170 of 280 days2016: Moderate 101 of 280 days2016: Unhealthy for Sensitive Groups 7 of 280 days2016: Unhealthy 2 of 280 days20162017: Good 258 of 316 days2017: Moderate 58 of 316 days2018: Good 273 of 365 days2018: Moderate 91 of 365 days2018: Unhealthy for Sensitive Groups 1 of 365 days20182019: Good 251 of 365 days2019: Moderate 114 of 365 days2020: Good 299 of 366 days2020: Moderate 67 of 366 days20202021: Good 259 of 365 days2021: Moderate 106 of 365 days2022: Good 303 of 365 days2022: Moderate 62 of 365 days20222023: Good 264 of 361 days2023: Moderate 96 of 361 days2023: Unhealthy for Sensitive Groups 1 of 361 days2024: Good 286 of 366 days2024: Moderate 80 of 366 days20242025: Good 312 of 365 days2025: Moderate 53 of 365 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 year0501001501990: 90th percentile AQI 481991: 90th percentile AQI 431995: 90th percentile AQI 281996: 90th percentile AQI 1011997: 90th percentile AQI 452003: 90th percentile AQI 862004: 90th percentile AQI 882005: 90th percentile AQI 1152006: 90th percentile AQI 1002007: 90th percentile AQI 1122008: 90th percentile AQI 972009: 90th percentile AQI 582010: 90th percentile AQI 872011: 90th percentile AQI 802012: 90th percentile AQI 842013: 90th percentile AQI 592014: 90th percentile AQI 622015: 90th percentile AQI 622016: 90th percentile AQI 742017: 90th percentile AQI 542018: 90th percentile AQI 582019: 90th percentile AQI 582020: 90th percentile AQI 542021: 90th percentile AQI 592022: 90th percentile AQI 532023: 90th percentile AQI 602024: 90th percentile AQI 582025: 90th percentile AQI 531990: Median AQI 241991: Median AQI 241995: Median AQI 211996: Median AQI 441997: Median AQI 312003: Median AQI 612004: Median AQI 532005: Median AQI 582006: Median AQI 552007: Median AQI 652008: Median AQI 492009: Median AQI 402010: Median AQI 452011: Median AQI 452012: Median AQI 442013: Median AQI 432014: Median AQI 442015: Median AQI 432016: Median AQI 472017: Median AQI 412018: Median AQI 392019: Median AQI 432020: Median AQI 382021: Median AQI 422022: Median AQI 392023: Median AQI 422024: Median AQI 422025: Median AQI 39199019951997200420062008201020122014201620182020202220242025
  • 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)19955%
Ozone16645%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253653125300003953100PM2.5
20243662868000004258100PM2.5
20233612649610004260107PM2.5
2022365303620000395377PM2.5
20213652591060000425990PM2.5
2020366299670000385497PM2.5
20193652511140000435893PM2.5
20183652739110003958133PM2.5
2017316258580000415487Ozone
201628017010172004774169Ozone
20152761859100004362100Ozone
20142781849220004462101Ozone
2013281209720000435980Ozone
201224317159112004484177Ozone
201124516470110004580147Ozone
20102371577280004587133Ozone
20092402033610004058136Ozone
200824413396150004997136Ozone
2007279831543570065112177Ozone
20062751161322520055100166Ozone
20052821001364510058115156Ozone
2004278128137121005388151Ozone
20034710370000618698PM2.5
1997343310000314553Ozone
1996366238903080044101174Ozone
1995616100000212833NO2
1991363600000244346PM10
1990252410000244854PM10

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 Tennessee with a similar median AQI in 2025

All monitored counties in Tennessee

Source: U.S. EPA AirData, “Annual AQI by County” files for 1990–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem