Air Quality in Indiana

Indiana has 40 counties with EPA air quality monitoring. Air quality is generally improving across the state, with an average of 252 "Good" days per county per year. The best air quality is in Huntington (median AQI 31) and the most polluted is Montgomery (median AQI 55).

County	Median AQI	Max AQI	Good Days	Unhealthy Days	Trend	Top Pollutant
Allen	45	100	229	0	↓ improving	Ozone
Bartholomew	44	101	262	1	→ stable	Ozone
Boone	36	93	313	0	→ stable	Ozone
Brown	37	77	339	0	→ stable	Ozone
Carroll	36	90	317	0	→ stable	Ozone
Clark	47	150	216	4	↑ worsening	PM2.5
Delaware	44	97	240	0	→ stable	PM2.5
Dubois	39	70	265	0	→ stable	PM2.5
Elkhart	45	145	227	1	→ stable	PM2.5
Floyd	43	154	257	1	↓ improving	Ozone
Greene	42	97	266	0	→ stable	Ozone
Hamilton	44	108	244	1	→ stable	PM2.5
Hancock	34	97	165	0	↓ improving	Ozone
Hendricks	35	80	331	0	→ stable	Ozone
Henry	34	75	282	0	→ stable	PM2.5
Howard	44	93	241	0	→ stable	Ozone
Huntington	31	84	345	0	↓ improving	Ozone
Jackson	35	80	340	0	↓ improving	Ozone
Johnson	39	80	214	0	↓ improving	Ozone
Knox	38	90	314	0	→ stable	Ozone
LaPorte	41	115	257	2	→ stable	Ozone
Lake	52	166	162	5	→ stable	PM2.5
Madison	42	97	263	0	→ stable	Ozone
Marion	54	138	134	4	→ stable	PM2.5
Monroe	34	63	290	0	→ stable	PM2.5
Montgomery	55	83	32	0	↓ improving	PM2.5
Morgan	35	87	344	0	↓ improving	Ozone
Perry	39	90	286	0	→ stable	Ozone
Porter	44	112	243	2	→ stable	Ozone
Posey	37	122	340	1	→ stable	Ozone
Shelby	36	87	331	0	→ stable	Ozone
Spencer	34	68	132	0	→ stable	PM2.5
St. Joseph	45	119	237	2	→ stable	Ozone
Sullivan	39	59	23	0	→ stable	PM2.5
Tippecanoe	35	67	256	0	→ stable	PM2.5
Vanderburgh	46	119	227	2	→ stable	PM2.5
Vigo	47	112	204	1	→ stable	PM2.5
Wabash	36	84	324	0	→ stable	Ozone
Warrick	38	101	326	1	→ stable	Ozone
Whitley	35	70	278	0	→ stable	PM2.5