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| County | Site | Units | Max | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Bannock | Pocatello | µg/m³ | 10.6 | 7.3 | 7.5 | 7.6 | 7.7 | 8 | 8.2 | 8.4 | 8.7 | 9 | 9.2 | 9.3 | 9.7 | 10 | 10 | 10 | 10.2 | 10.3 | 10.4 | 10.6 | 10.3 | 10.4 | 10.4 | 10.4 | 10.4 |
| Boise | Idaho City | µg/m³ | 13 | 10.1 | 10.3 | 10.3 | 10.5 | 10.7 | 10.9 | 11.3 | 11.4 | 11.5 | 11.7 | 11.9 | 12.3 | 12 | 12.1 | 12.2 | 12.2 | 12.7 | 13 | 12.8 | 12.6 | 12.7 | 12.7 | 12.5 | 12.7 |
| Bonner | Sandpoint | µg/m³ | 7.2 | 5.9 | 5.9 | 6 | 6.1 | 6.1 | 6.2 | 6.2 | 6.2 | 6.3 | 6.4 | 6.4 | 6.3 | 6.2 | 6.1 | 6.1 | 6.2 | 6.1 | 6.4 | 6.6 | 7 | 7.1 | 7 | 7.2 | 7.2 |
| Bonneville | Idaho Falls | µg/m³ | 24.6 | 6.3 | 6.4 | 6.6 | 6.7 | 6.7 | 6.8 | 7 | 7.1 | 7.2 | 7.3 | 7.7 | 8.2 | 8.5 | 9.4 | 11 | 13 | 15 | 17.1 | 18.9 | 20.1 | 21 | 22.1 | 23.4 | 24.6 |
| Boundary | Bonners Ferry | µg/m³ | 3.6 | 2.5 | 2.6 | 2.7 | 2.7 | 3 | 3 | 3.2 | 3.2 | 3.3 | 3.5 | 3 | 3.3 | 3 | 2.9 | 2.9 | 3.1 | 3.2 | 3.2 | 3.4 | 3.6 | 3.6 | 3.5 | 3.6 | 3.5 |
| Canyon | Nampa | µg/m³ | 23.5 | 20.5 | 20.9 | 21.2 | 21.6 | 21.9 | 22.4 | 22.7 | 22.9 | 23.3 | 23.5 | 23.5 | 23.5 | 23.4 | 23.2 | 23.2 | 22.7 | 22.2 | 21.4 | 20.7 | 20.2 | 20 | 19.4 | 18.8 | 18 |
| Clearwater | Orofino - Nez Perce Tribe | µg/m³ | 9.1 | 9 | 9 | 9.1 | 8.8 | 8.6 | 8.3 | 8.4 | 8.1 | 8.2 | 8.2 | 8.2 | 8.1 | 7.9 | 8 | 8 | 8.1 | 8 | 8.3 | 8.2 | 8.4 | 8.5 | 8.5 | 8 | 7.6 |
| Idaho | Cottonwood | µg/m³ | 8.5 | 7.9 | 7.8 | 7.9 | 8 | 7.8 | 8 | 7.7 | 7.7 | 7.7 | 7.7 | 8 | 7.7 | 7.6 | 7.7 | 7.6 | 7.6 | 7.3 | 7.6 | 7.8 | 7.9 | 8.1 | 8.1 | 8.2 | 8.5 |
| Idaho | Grangeville | µg/m³ | 6.9 | 6.8 | 6.8 | 6.8 | 6.9 | 6.9 | 6.9 | 6.9 | 6.6 | 6.6 | 6.8 | 6.7 | 6.5 | 6.3 | 6.2 | 6.2 | 6.3 | 6.4 | 6.4 | 6.5 | 6.2 | 6.4 | 6.6 | 6.7 | 6.7 |
| Kootenai | Coeur d'Alene | µg/m³ | 7.1 | 6.3 | 6.3 | 6.4 | 6.5 | 6.5 | 6.5 | 6.7 | 6.8 | 7 | 7.1 | 7 | 7 | 7 | 6.9 | 7 | 7 | 6.9 | 6.8 | 6.8 | 6.7 | 6.5 | 6.4 | 6.4 | 6.4 |
| Latah | Juliaetta | µg/m³ | 8.7 | 8.2 | 8.3 | 8.4 | 8.7 | 8.7 | 8.6 | 8.6 | 8.6 | 8.1 | 8.2 | 8 | 7.7 | 8 | 7.5 | 7.7 | 7.5 | 7.4 | 7.3 | 7.6 | 7.5 | 7.4 | 7.4 | 7.5 | 7.4 |
| Lemhi | Salmon | µg/m³ | 32.8 | 32.8 | 32.8 | 32.4 | 32.4 | 32.2 | 32.3 | 32.5 | 31.8 | 31.6 | 31.3 | 31.2 | 30.9 | 30.2 | 29.7 | 28.7 | 27.8 | 26.9 | 26.1 | 25.2 | 24.5 | 23.7 | 22.9 | 21.9 | 21.4 |
| Lewis | Reubens - Nez Perce Tribe | µg/m³ | 8.2 | 8.2 | 8 | 7.7 | 7.5 | 7.3 | 7.4 | 7.2 | 7.2 | 7.2 | 7 | 7.2 | 7.2 | 7 | 7.2 | 7.4 | 7.5 | 7.2 | 7.5 | 7.3 | 7.2 | 7.4 | 7.1 | 7.4 | 7.2 |
| Lewis/Idaho | Kamiah - Nez Perce Tribe | µg/m³ | 8.5 | 8.2 | 8.2 | 8.2 | 8 | 8.3 | 8 | 8 | 8 | 7.5 | 8.3 | 8.5 | 8.1 | 8 | 7.9 | 8.1 | 7.9 | 7.9 | 7.9 | 8 | 8 | 8.2 | 8 | 8 | 8 |
| Nez Perce | Lapwai - Nez Perce Tribe | µg/m³ | 7.1 | 7.1 | 7 | 6.8 | 6.7 | 6.5 | 6.3 | 6.2 | 6.3 | 6.5 | 6.4 | 6.3 | 6.2 | 6.1 | 5.9 | 5.8 | 6.2 | 5.9 | 6.2 | 6.5 | 6.4 | 6.7 | 6.8 | 6.8 | 6.7 |
| Nez Perce | Lewiston | µg/m³ | 11.8 | 11.8 | 11.7 | 11.5 | 11.4 | 11.2 | 11.1 | 10.9 | 10.7 | 10.2 | 10.4 | 9.8 | 9.7 | 9.6 | 9.2 | 9.2 | 9.1 | 9.1 | 9.3 | 10 | 10.2 | 10.3 | 10.3 | 10.3 | 10.4 |
| Shoshone | Pinehurst | µg/m³ | 13.2 | 12.2 | 12.1 | 12 | 12.2 | 12.3 | 12.7 | 12.8 | 12.9 | 12.9 | 12.8 | 12.7 | 12.7 | 12.6 | 12.3 | 12.2 | 12.2 | 12.2 | 12.2 | 12.4 | 13 | 13.2 | 12.7 | 12.8 | 12.6 |
| Twin Falls | Twin Falls | µg/m³ | 9.1 | 9.1 | 8.9 | 8.6 | 8.4 | 8.2 | 7.7 | 7.5 | 7.1 | 7 | 6.6 | 6.6 | 6.5 | 6.4 | 6.5 | 6.4 | 6.3 | 6.3 | 6.2 | 6.2 | 6.4 | 6.5 | 6.8 | 7 | 7.1 |

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