EnviroNearby

Marshall County, Kentucky air quality history

Daily Air Quality Index summaries from EPA monitors in Marshall, Kentucky, 1991–2014.

100%
Good days in 2014
15
Median daily AQI, 2014
0
Days above 100 in 2014
41
Days with an AQI in 2014 (of 365)

In 2014, EPA reported a daily Air Quality Index (AQI) for Marshall, Kentucky on 41 days. 41 of those days (100%) were in the Good range, and the median daily AQI was 15. That median is lower than the typical monitored county in Kentucky (median 42 across 27 counties), and lower than the typical monitored U.S. county (42). The main pollutant was coarse particles (PM10) on 41 days.

EPA did not report an AQI for every day of 2014 here (41 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

The most recent year with data for this county is 2014; EPA's files for 2015–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (2009, 2010, 2011, 2012, 2013, 2014…) 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%1991: Good 33 of 43 days1991: Moderate 10 of 43 days19911992: Good 54 of 57 days1992: Moderate 3 of 57 days1993: Good 51 of 56 days1993: Moderate 5 of 56 days19931994: Good 55 of 57 days1994: Moderate 2 of 57 days1995: Good 58 of 61 days1995: Moderate 3 of 61 days19951996: Good 59 of 60 days1996: Moderate 1 of 60 days1997: Good 56 of 59 days1997: Moderate 3 of 59 days19971998: Good 52 of 56 days1998: Moderate 4 of 56 days1999: Good 47 of 52 days1999: Moderate 5 of 52 days19992000: Good 39 of 41 days2000: Moderate 2 of 41 days2001: Good 60 of 60 days20012002: Good 58 of 59 days2002: Moderate 1 of 59 days2003: Good 59 of 59 days20032004: Good 11 of 11 days2005: Good 14 of 14 days20052006: Good 53 of 54 days2006: Moderate 1 of 54 days2007: Good 54 of 55 days2007: Moderate 1 of 55 days20072008: Good 58 of 58 days2009: Good 55 of 55 days20092010: Good 57 of 57 days2011: Good 59 of 59 days20112012: Good 57 of 57 days2013: Good 58 of 58 days20132014: Good 41 of 41 days2014
  • 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 year0501001991: 90th percentile AQI 551992: 90th percentile AQI 441993: 90th percentile AQI 481994: 90th percentile AQI 431995: 90th percentile AQI 421996: 90th percentile AQI 401997: 90th percentile AQI 381998: 90th percentile AQI 481999: 90th percentile AQI 492000: 90th percentile AQI 422001: 90th percentile AQI 312002: 90th percentile AQI 312003: 90th percentile AQI 302004: 90th percentile AQI 212005: 90th percentile AQI 312006: 90th percentile AQI 252007: 90th percentile AQI 332008: 90th percentile AQI 262009: 90th percentile AQI 232010: 90th percentile AQI 242011: 90th percentile AQI 252012: 90th percentile AQI 222013: 90th percentile AQI 192014: 90th percentile AQI 251991: Median AQI 291992: Median AQI 201993: Median AQI 221994: Median AQI 241995: Median AQI 221996: Median AQI 221997: Median AQI 161998: Median AQI 241999: Median AQI 292000: Median AQI 222001: Median AQI 192002: Median AQI 182003: Median AQI 182004: Median AQI 172005: Median AQI 132006: Median AQI 172007: Median AQI 182008: Median AQI 142009: Median AQI 132010: Median AQI 162011: Median AQI 152012: Median AQI 142013: Median AQI 112014: Median AQI 151991199319951997199920012003200520072009201120132014
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2014

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
Coarse particles (PM10)41100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2014414100000152537PM10
2013585800000111922PM10
2012575700000142230PM10
2011595900000152531PM10
2010575700000162431PM10
2009555500000132331PM10
2008585800000142631PM10
2007555410000183357PM10
2006545310000172555PM10
2005141400000133150PM10
2004111100000172126PM10
2003595900000183040PM10
2002595810000183152PM10
2001606000000193149PM10
2000413920000224253PM10
1999524750000294959PM10
1998565240000244865PM10
1997595630000163865PM10
1996605910000224083PM10
1995615830000224259PM10
1994575520000244360PM10
1993565150000224857PM10
1992575430000204463PM10
19914333100000295567PM10

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 Kentucky

Source: U.S. EPA AirData, “Annual AQI by County” files for 1991–2014 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem