Belmont County, Ohio air quality history

Daily Air Quality Index summaries from EPA monitors in Belmont, Ohio, 1988–2025.

63%

Good days in 2025

Median daily AQI, 2025

Days above 100 in 2025

181

Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Belmont, Ohio on 181 days. 114 of those days (63%) were in the Good range, and the median daily AQI was 42. That median is about the same as the typical monitored county in Ohio (median 43 across 36 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 161 days. Across the years with fuller monitoring, the share of Good days fell: an average of 91% in 1989–1991 versus 75% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (181 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.

Years with fewer than 120 monitored days (1999, 2000, 2001, 2002, 2003, 2004…) 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.

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 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.

Pollutant	Days as main pollutant	Share of monitored days
Fine particles (PM2.5)	161	89%
Coarse particles (PM10)	18	10%
Nitrogen dioxide (NO₂)	2	1%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Unhealthy for Sensitive Groups	Unhealthy	Median AQI	90th pct.	Max AQI	Main pollutant
2025	181	114	66	1	0	42	65	123	PM2.5
2024	366	289	77	0	0	32	55	77	PM2.5
2023	353	288	64	0	1	31	54	181	PM2.5
2022	360	338	22	0	0	15	44	64	NO2
2021	363	320	43	0	0	14	53	77	NO2
2020	366	347	19	0	0	13	40	69	NO2
2019	365	327	38	0	0	15	51	69	NO2
2018	365	331	34	0	0	18	48	72	NO2
2017	365	333	32	0	0	16	48	77	NO2
2016	366	320	46	0	0	17	53	100	NO2
2015	184	162	22	0	0	17	52	79	NO2
2004	5	5	0	0	0	16	19	19	PM10
2003	60	59	1	0	0	20	31	54	PM10
2002	56	56	0	0	0	20	33	49	PM10
2001	59	58	1	0	0	21	39	53	PM10
2000	59	54	5	0	0	24	49	59	PM10
1999	59	56	3	0	0	22	46	59	PM10
1998	59	59	0	0	0	19	44	50	PM10
1997	49	47	2	0	0	23	42	94	PM10
1996	62	59	3	0	0	24	45	67	PM10
1995	63	57	6	0	0	28	50	69	PM10
1994	62	54	8	0	0	28	54	62	PM10
1993	61	56	5	0	0	26	49	66	PM10
1992	82	77	5	0	0	22	44	64	PM10
1991	177	168	9	0	0	22	44	75	PM10
1990	180	171	9	0	0	23	44	76	PM10
1989	151	127	24	0	0	27	54	73	PM10
1988	51	48	3	0	0	26	44	64	PM10

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 Ohio with a similar median AQI in 2025

All monitored counties in Ohio

Source: U.S. EPA AirData, “Annual AQI by County” files for 1988–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem