EnviroNearby

Hancock County, Ohio air quality history

Daily Air Quality Index summaries from EPA monitors in Hancock, Ohio, 1991–2011.

100%
Good days in 2011
21
Median daily AQI, 2011
0
Days above 100 in 2011
15
Days with an AQI in 2011 (of 365)

In 2011, EPA reported a daily Air Quality Index (AQI) for Hancock, Ohio on 15 days. 15 of those days (100%) were in the Good range, and the median daily AQI was 21. That median is lower than the typical monitored county in Ohio (median 47 across 37 counties), and lower than the typical monitored U.S. county (44). The main pollutant was coarse particles (PM10) on 15 days.

EPA did not report an AQI for every day of 2011 here (15 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 2011; EPA's files for 2012–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (2006, 2007, 2008, 2009, 2010, 2011…) 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 22 of 22 days19911992: Good 56 of 56 days1993: Good 61 of 61 days19931994: Good 61 of 61 days1995: Good 61 of 61 days19951996: Good 58 of 58 days1997: Good 49 of 49 days19971998: Good 56 of 56 days1999: Good 48 of 48 days19992000: Good 50 of 50 days2001: Good 55 of 55 days20012002: Good 45 of 45 days2003: Good 40 of 40 days20032004: Good 54 of 54 days2005: Good 61 of 61 days20052006: Good 56 of 56 days2007: Good 54 of 54 days20072008: Good 59 of 59 days2009: Good 54 of 54 days20092010: Good 61 of 61 days2011: Good 15 of 15 days2011
  • 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 391992: 90th percentile AQI 391993: 90th percentile AQI 371994: 90th percentile AQI 401995: 90th percentile AQI 381996: 90th percentile AQI 351997: 90th percentile AQI 441998: 90th percentile AQI 391999: 90th percentile AQI 282000: 90th percentile AQI 352001: 90th percentile AQI 322002: 90th percentile AQI 322003: 90th percentile AQI 312004: 90th percentile AQI 292005: 90th percentile AQI 322006: 90th percentile AQI 292007: 90th percentile AQI 312008: 90th percentile AQI 272009: 90th percentile AQI 292010: 90th percentile AQI 342011: 90th percentile AQI 391991: Median AQI 291992: Median AQI 261993: Median AQI 301994: Median AQI 321995: Median AQI 281996: Median AQI 241997: Median AQI 281998: Median AQI 291999: Median AQI 192000: Median AQI 252001: Median AQI 232002: Median AQI 232003: Median AQI 232004: Median AQI 232005: Median AQI 232006: Median AQI 232007: Median AQI 222008: Median AQI 202009: Median AQI 192010: Median AQI 222011: Median AQI 2119911993199519971999200120032005200720092011
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2011

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)15100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2011151500000213943PM10
2010616100000223439PM10
2009545400000192939PM10
2008595900000202731PM10
2007545400000223133PM10
2006565600000232940PM10
2005616100000233242PM10
2004545400000232939PM10
2003404000000233136PM10
2002454500000233238PM10
2001555500000233238PM10
2000505000000253544PM10
1999484800000192833PM10
1998565600000293942PM10
1997494900000284444PM10
1996585800000243544PM10
1995616100000283844PM10
1994616100000324045PM10
1993616100000303744PM10
1992565600000263944PM10
1991222200000293944PM10

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 Ohio

Source: U.S. EPA AirData, “Annual AQI by County” files for 1991–2011 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem