Daily Air Quality Index summaries from EPA monitors in Grant, Oregon, 2005–2025.
63%
Good days in 2025
37
Median daily AQI, 2025
0
Days above 100 in 2025
364
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Grant, Oregon on 364 days. 230 of those days (63%) were in the Good range, and the median daily AQI was 37. That median is higher than the typical monitored county in Oregon (median 29 across 21 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 364 days. Across the years with fuller monitoring, the share of Good days fell: an average of 68% in 2005–2007 versus 57% in 2023–2025.
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)
364
100%
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
364
230
134
0
0
0
0
37
67
89
PM2.5
2024
366
189
158
5
13
1
0
49
74
204
PM2.5
2023
365
207
156
2
0
0
0
44
68
110
PM2.5
2022
365
198
166
1
0
0
0
46
72
108
PM2.5
2021
365
178
177
5
5
0
0
51
74
175
PM2.5
2020
364
196
161
1
5
0
1
44
70
393
PM2.5
2019
349
205
143
1
0
0
0
41
65
103
PM2.5
2018
362
206
153
1
2
0
0
45
66
176
PM2.5
2017
358
205
141
10
2
0
0
42
70
175
PM2.5
2016
341
246
95
0
0
0
0
29
61
85
PM2.5
2015
363
215
139
4
5
0
0
42
64
172
PM2.5
2014
359
216
141
1
1
0
0
42
67
154
PM2.5
2013
351
153
195
3
0
0
0
52
72
145
PM2.5
2012
363
226
137
0
0
0
0
39
67
100
PM2.5
2011
352
209
140
3
0
0
0
41
71
122
PM2.5
2010
365
242
122
1
0
0
0
33
63
137
PM2.5
2009
336
200
134
2
0
0
0
39
65
106
PM2.5
2008
328
204
122
2
0
0
0
40
64
106
PM2.5
2007
355
243
107
4
1
0
0
34
66
172
PM2.5
2006
364
244
120
0
0
0
0
39
63
94
PM2.5
2005
363
244
117
2
0
0
0
33
65
108
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.
Counties in Oregon with a similar median AQI in 2025
