SmogRank / United States / Utah / Millcreek
Millcreek, month by month
Millcreek has a measured daily mean on 1,297 days since 11 January 2023. Its worst month was December 2023, at 66 US AQI (16.9 µg/m³), 234th of 2,247 cities on that month's world ranking. Its cleanest was February 2024, at 29 US AQI (5.2 µg/m³). 2025 averaged 51 US AQI (9.2 µg/m³), against 52 US AQI (9.6 µg/m³) in 2024.
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
3 months
| Month | Why |
|---|---|
| Apr 2023 | 3 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 20 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Jan 2023 | 7 of 31 days measured; a month needs 22. The others: 14 with under 18 hours of readings or readings that failed our checks. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Millcreek's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| December 2023 | 6616.9 µg/m³ | 234thof 2,247 | – |
| December 2024 | 6516.7 µg/m³ | 392ndof 2,616 | – |
| February 2023 | 6516.5 µg/m³ | 260thof 1,129 | Utah and Idaho, United States, February 2023 |
| January 2026 | 6315.7 µg/m³ | 717thof 2,617 | – |
| July 2024 | 6315.3 µg/m³ | 173rdof 2,566 | North-western United States and Canada, July 2024 |
| November 2023 | 5812.7 µg/m³ | 243rdof 2,243 | Utah and Idaho, United States, November 2023 |
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.
Millcreek's worst days
| Day | US AQI | Episode |
|---|---|---|
| 4 Feb 2023 | 13951.1 µg/m³ | Utah and Idaho, United States, February 2023 |
| 3 Feb 2023 | 12846.5 µg/m³ | Utah and Idaho, United States, February 2023 |
| 5 Dec 2024 | 12645.5 µg/m³ | – |
| 6 Dec 2024 | 12344.5 µg/m³ | – |
| 1 Jan 2024 | 11742.1 µg/m³ | – |
| 2 Feb 2023 | 11541.0 µg/m³ | Utah and Idaho, United States, February 2023 |
| 4 Dec 2024 | 11240.0 µg/m³ | – |
| 11 Sept 2024 | 10737.8 µg/m³ | North-western United States and Canada, 4 to 11 September 2024 |
| 3 Dec 2024 | 10336.3 µg/m³ | – |
| 1 Jan 2026 | 10035.4 µg/m³ | – |
Daily means, the highest since 11 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, Millcreek, United States, 11 Jan 2023 – 11 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/millcreek/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.
Millcreek now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 19:07 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).