SmogRank / United States / Idaho / Meridian
Meridian, month by month
Meridian has a measured daily mean on 963 days since 1 January 2023. Its worst month was July 2024, at 82 US AQI (25.9 µg/m³), 71st of 2,566 cities on that month's world ranking. Its cleanest was May 2024, at 17 US AQI (3.1 µg/m³). 2024 averaged 52 US AQI (9.7 µg/m³), against 36 US AQI (6.4 µg/m³) in 2023.
Every month since 2023
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
Months without a mean, and why
14 months
| Month | Why |
|---|---|
| Oct 2026 | 7 of 11 days measured; a month needs 8. The others: 3 with no readings from the monitor, 1 with readings for part of the day (a day needs 18 hours). |
| Jul 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jun 2026 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| May 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Apr 2026 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Mar 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Feb 2026 | No day measured. The others: 28 with under 18 hours of readings or readings that failed our checks. |
| Jan 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Dec 2025 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Nov 2025 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Oct 2025 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Sep 2025 | 9 of 30 days measured; a month needs 21. The others: 21 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 11 of 31 days measured; a month needs 22. The others: 20 missing from OpenAQ's archive. |
| Feb 2023 | 3 of 28 days measured; a month needs 20. The others: 25 missing from OpenAQ's archive. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Meridian's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| July 2024 | 8225.9 µg/m³ | 71stof 2,566 | North-western United States and Canada, July 2024 |
| August 2024 | 8024.5 µg/m³ | 70thof 2,010 | North-western United States, August and September 2024 Oregon, Idaho and Utah, United States, August 2024 |
| August 2026 | 7521.9 µg/m³ | 209thof 2,896 | North-western United States and Canada, 4 to 22 August 2026 North-western United States and Canada, July and August 2026 |
| September 2024 | 6315.5 µg/m³ | 156thof 2,010 | North-western United States and Canada, 4 to 11 September 2024 North-western United States, August and September 2024 |
| January 2024 | 5310.1 µg/m³ | 870thof 2,385 | – |
| July 2023 | 519.1 µg/m³ | 751stof 1,432 | – |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Meridian's worst days
Daily means, the highest since 1 Jan 2023; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.
Use this history
SmogRank, PM2.5 monthly and daily means, Meridian, United States, 1 Jan 2023 – 7 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/meridian/history (accessed 12 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.
Meridian now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 23:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).