SmogRank / United States / Texas / Pasadena
Pasadena, month by month
Pasadena has a measured daily mean on 1,300 days since 1 January 2023. Its worst month was May 2024, at 64 US AQI (16.0 µg/m³), 235th of 2,684 cities on that month's world ranking. Its cleanest was March 2026, at 42 US AQI (7.6 µg/m³). 2025 averaged 53 US AQI (10.4 µg/m³), against 54 US AQI (10.6 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
2 months
| Month | Why |
|---|---|
| Nov 2025 | 18 of 30 days measured; a month needs 21. The others: 12 with under 18 hours of readings or readings that failed our checks. |
| Jun 2025 | 20 of 30 days measured; a month needs 21. The others: 10 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.
Pasadena's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| May 2024 | 6416.0 µg/m³ | 235thof 2,684 | Southern United States and Mexico, 19 to 28 May 2024 Southern United States and Mexico, 7 to 10 May 2024 |
| May 2023 | 6013.9 µg/m³ | 172ndof 1,600 | Southern United States, May 2023 |
| March 2023 | 6013.7 µg/m³ | 106thof 911 | – |
| July 2023 | 6013.7 µg/m³ | 222ndof 1,432 | – |
| July 2025 | 5812.8 µg/m³ | 682ndof 2,889 | – |
| July 2024 | 5712.5 µg/m³ | 360thof 2,566 | Southern and eastern United States and Mexico, July and August 2024 |
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.
Pasadena's worst days
| Day | US AQI | Episode |
|---|---|---|
| 1 Jan 2024 | 16575.6 µg/m³ | Texas, Louisiana and Mississippi, United States, January 2024 |
| 27 May 2024 | 12043.1 µg/m³ | Southern United States and Mexico, 19 to 28 May 2024 |
| 9 May 2024 | 11239.9 µg/m³ | Southern United States and Mexico, 7 to 10 May 2024 |
| 1 Jan 2026 | 11039.2 µg/m³ | Texas and Louisiana, United States, December 2025 to January 2026 |
| 31 Jul 2024 | 9532.5 µg/m³ | Southern and eastern United States and Mexico, July and August 2024 |
| 15 Mar 2023 | 8829.0 µg/m³ | – |
| 27 Feb 2023 | 8728.5 µg/m³ | Texas and Oklahoma, United States, February 2023 |
| 15 Mar 2025 | 8728.5 µg/m³ | United States and Mexico, March 2025 Eastern United States, March 2025 |
| 24 May 2023 | 8527.2 µg/m³ | Southern United States, May 2023 |
| 26 May 2024 | 8427.0 µg/m³ | Southern United States and Mexico, 19 to 28 May 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, Pasadena, United States, 1 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/pasadena/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.
Pasadena now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 17:07 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).