SmogRank / United States / Colorado / Ken Caryl
Ken Caryl, month by month
Ken Caryl has a measured daily mean on 1,247 days since 1 January 2023. Its worst month was May 2023, at 56 US AQI (11.9 µg/m³), 272nd of 1,600 cities on that month's world ranking. Its cleanest was December 2024, at 11 US AQI (2.0 µg/m³). 2025 averaged 26 US AQI (4.6 µg/m³), against 24 US AQI (4.4 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
2 months
| Month | Why |
|---|---|
| Oct 2026 | 6 of 11 days measured; a month needs 8. The others: 2 with no readings from the monitor, 3 with readings for part of the day (a day needs 18 hours). |
| Dec 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. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Ken Caryl's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| May 2023 | 5611.9 µg/m³ | 272ndof 1,600 | North-western United States and Canada, May 2023 |
| July 2024 | 478.5 µg/m³ | 1,174thof 2,566 | North-western United States and Canada, July 2024 |
| August 2026 | 468.2 µg/m³ | 1,533rdof 2,896 | North-western United States and Canada, July and August 2026 |
| July 2026 | 417.4 µg/m³ | 2,036thof 2,784 | North-western United States and Canada, July and August 2026 |
| February 2025 | 417.3 µg/m³ | 1,752ndof 2,633 | – |
| August 2025 | 407.2 µg/m³ | 2,101stof 2,901 | – |
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.
Ken Caryl's worst days
| Day | US AQI | Episode |
|---|---|---|
| 19 May 2023 | 17488.0 µg/m³ | North-western United States and Canada, May 2023 |
| 20 May 2023 | 15256.9 µg/m³ | North-western United States and Canada, May 2023 |
| 22 May 2023 | 10035.4 µg/m³ | North-western United States and Canada, May 2023 |
| 23 May 2023 | 9532.5 µg/m³ | North-western United States and Canada, May 2023 |
| 4 Aug 2026 | 8728.5 µg/m³ | North-western United States and Canada, July and August 2026 |
| 23 Jul 2024 | 8628.0 µg/m³ | North-western United States and Canada, July 2024 |
| 24 Jul 2024 | 8326.3 µg/m³ | North-western United States and Canada, July 2024 |
| 6 Jul 2026 | 8326.1 µg/m³ | – |
| 5 Aug 2026 | 7823.6 µg/m³ | – |
| 22 Jul 2024 | 7521.8 µg/m³ | North-western United States and Canada, July 2024 |
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, Ken Caryl, United States, 1 Jan 2023 – 9 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/ken-caryl/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.
Ken Caryl 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).