Chase County, Kansas air quality history

Daily Air Quality Index summaries from EPA monitors in Chase, Kansas, 2002–2025.

87%

Good days in 2024

Median daily AQI, 2024

Days above 100 in 2024

122

Days with an AQI in 2024 (of 366)

In 2024, EPA reported a daily Air Quality Index (AQI) for Chase, Kansas on 122 days. 106 of those days (87%) were in the Good range, and the median daily AQI was 29. That median is lower than the typical monitored county in Kansas (median 44 across 11 counties), and lower than the typical monitored U.S. county (41). The main pollutant was fine particles (PM2.5) on 122 days. Across the years with fuller monitoring, the share of Good days rose: an average of 75% in 2008–2010 versus 88% in 2021–2024.

EPA did not report an AQI for every day of 2024 here (122 of 366 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 (2016, 2017, 2018, 2019, 2023, 2025…) 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, 2024

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)	122	100%

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	99	82	17	0	0	31	54	95	PM2.5
2024	122	106	16	0	0	29	53	94	PM2.5
2023	117	98	19	0	0	29	54	79	PM2.5
2022	121	110	11	0	0	25	49	66	PM2.5
2021	120	102	18	0	0	27	52	99	PM2.5
2020	121	110	11	0	0	24	47	63	PM2.5
2019	118	105	12	1	0	27	51	113	PM2.5
2018	116	96	20	0	0	30	53	67	PM2.5
2017	118	100	18	0	0	28	52	65	PM2.5
2016	118	105	11	2	0	24	52	148	PM2.5
2015	119	97	22	0	0	26	55	85	PM2.5
2014	120	84	35	0	1	33	58	154	PM2.5
2013	120	93	27	0	0	34	57	71	PM2.5
2012	117	88	29	0	0	35	56	90	PM2.5
2011	117	86	31	0	0	35	61	95	PM2.5
2010	121	93	27	1	0	31	56	138	PM2.5
2009	121	94	27	0	0	34	55	69	PM2.5
2008	120	85	35	0	0	36	58	75	PM2.5
2007	113	75	38	0	0	39	62	84	PM2.5
2006	116	87	29	0	0	35	59	77	PM2.5
2005	116	69	47	0	0	41	66	96	PM2.5
2004	118	83	35	0	0	34	59	93	PM2.5
2003	119	69	48	1	1	43	61	153	PM2.5
2002	27	21	6	0	0	23	63	64	PM2.5

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 Kansas

Source: U.S. EPA AirData, “Annual AQI by County” files for 2002–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem