Daily Air Quality Index summaries from EPA monitors in Lafourche, Louisiana, 1983–2025.
67%
Good days in 2025
44
Median daily AQI, 2025
1
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Lafourche, Louisiana on 365 days. 246 of those days (67%) were in the Good range, and the median daily AQI was 44. That median is about the same as the typical monitored county in Louisiana (median 42 across 21 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 256 days. Across the years with fuller monitoring, the share of Good days fell: an average of 77% in 1983–1990 versus 55% in 2023–2025.
Years with fewer than 120 monitored days (1984) 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)
256
70%
Ozone
109
30%
Year-by-year data
Annual AQI summary by year
Year
Days with AQI
Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous
Median AQI
90th pct.
Max AQI
Main pollutant
2025
365
246
118
1
0
0
0
44
57
109
PM2.5
2024
362
197
164
1
0
0
0
48
61
115
PM2.5
2023
365
153
211
1
0
0
0
53
69
101
PM2.5
2022
351
238
112
1
0
0
0
43
59
109
PM2.5
2021
347
204
143
0
0
0
0
45
60
84
PM2.5
2020
366
212
153
1
0
0
0
48
61
115
PM2.5
2019
360
173
185
2
0
0
0
51
63
126
PM2.5
2018
362
280
82
0
0
0
0
39
56
90
Ozone
2017
365
300
65
0
0
0
0
38
54
87
Ozone
2016
366
306
60
0
0
0
0
39
54
93
Ozone
2015
365
277
88
0
0
0
0
38
58
97
PM2.5
2014
363
268
94
1
0
0
0
41
58
105
Ozone
2013
365
290
74
1
0
0
0
40
57
146
Ozone
2012
359
251
104
4
0
0
0
41
69
133
Ozone
2011
365
238
121
6
0
0
0
44
67
133
PM2.5
2010
364
212
144
8
0
0
0
46
70
129
PM2.5
2009
365
232
131
2
0
0
0
45
61
112
PM2.5
2008
342
161
175
6
0
0
0
51
71
126
PM2.5
2007
365
172
179
13
1
0
0
52
80
154
PM2.5
2006
365
132
217
14
2
0
0
54
87
182
PM2.5
2005
360
133
203
23
1
0
0
55
93
154
PM2.5
2004
366
174
173
19
0
0
0
52
80
143
PM2.5
2003
362
172
163
27
0
0
0
52
90
147
PM2.5
2002
351
227
118
6
0
0
0
44
65
115
PM2.5
2001
365
191
153
17
4
0
0
49
93
172
Ozone
2000
354
156
158
37
3
0
0
52
108
187
Ozone
1999
261
182
50
25
4
0
0
43
105
185
Ozone
1998
352
273
48
25
5
1
0
37
90
204
Ozone
1997
362
275
69
16
2
0
0
36
87
166
Ozone
1996
366
299
59
8
0
0
0
33
71
140
Ozone
1995
339
250
43
33
12
1
0
36
119
205
Ozone
1994
347
281
50
12
4
0
0
33
74
185
Ozone
1993
356
289
55
12
0
0
0
37
77
133
Ozone
1992
340
291
46
3
0
0
0
34
61
112
Ozone
1991
348
296
40
11
1
0
0
32
77
154
Ozone
1990
356
279
51
24
2
0
0
37
87
200
Ozone
1989
279
211
46
21
1
0
0
32
90
172
Ozone
1984
98
84
9
5
0
0
0
26
80
133
Ozone
1983
138
106
21
10
1
0
0
33
90
154
Ozone
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 Louisiana with a similar median AQI in 2025
