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Washington Court House, OH Air Quality

EPA monitor data through 2022 · Updated August 13, 2026 · Methods

In 2022, Washington Court House, OH recorded 0 days above an Air Quality Index of 100, the level at which EPA begins warning sensitive groups, out of 130 days with monitoring data. Most of those bad days were driven by ozone and fine particles equally. Under the AQI rules that applied before 2013, the same air would have scored 0 days. Since 2000, unhealthy days are 100% lower on a consistent definition.

Unhealthy days, 2022

AQI above 100

Same air, pre-2013 rules

for comparison with older reports

Good-air days

128

AQI 50 or below

Days monitored

130

partial coverage

Unhealthy days by year, scored two ways

EPA changed what an AQI of 100 means in 2013 and again in 2015, so a count published before those changes is not comparable to one published after. Each panel below applies a single fixed rulebook to every year, so each is internally consistent. Why this matters.

Scored by today's rules

Scored by the pre-2013 rules

Faded columns mark years with fewer than 300 monitored days, where the count is not comparable.

Ozone since 1990

The index counts above only start in 2000, because nationwide fine-particle monitoring did not exist before 1999 and an index without it would measure the monitoring network rather than the air. Ozone does have a 35-year record. This is Washington Court House, OH's, from EPA's long-running trend monitors: 96 ppb in 1990 to 53 ppb in 2024, 45% lower.

Peak ozone, 1990 to 2024

Annual fourth-highest daily maximum 8-hour ozone, parts per billion, averaged across 1 long-running monitor in the area. The dashed line is the current standard, 70 ppb. Holding the monitor set still is what makes a 35-year comparison meaningful, and it is also why these values differ from the design value used for compliance. Source: EPA air quality statistics by city.

What 2022 looked like

Air quality category	Days	Share of monitored days
Good	128	98%
Moderate	2	2%
Unhealthy for sensitive groups	0	0%
Unhealthy or worse	0	0%

Median AQI 34 · 90th-percentile AQI 46 · worst day 64. Scored under current rules.

Statewide context

Washington Court House, OH sits in Ohio.

The full series

Year	Unhealthy days, current rules	Pre-2013 rules	Days monitored
2000	21	11	361
2001	18	8	365
2002	37	27	358
2003	11	7	353
2004	8	1	354
2005	28	15	357
2006	6	3	358
2007	22	9	364
2008	2	1	351
2009	0	0	361
2010	5	1	356
2011	9	3	344
2012	10	4	357
2013	2	0	351
2014	2	1	352
2015	3	0	336
2016	1	0	356
2017	1	0	360
2018	0	0	365
2019	0	0	362
2020	0	0	343
2021	0	0	365
2022	0	0	130

Sources

EPA AirData daily monitor files, recomputed under both breakpoint tables. Methods and validation.
Download the full dataset for every state and metro.