SmogRank / United States / Oregon / Portland
Portland, month by month
Portland has a measured daily mean on 1,362 days since 1 January 2023. Its worst month was August 2026, at 52 US AQI (9.4 µg/m³), 1,064th of 2,896 cities on that month's world ranking. Its cleanest was June 2024, at 15 US AQI (2.7 µg/m³). 2025 averaged 28 US AQI (5.0 µg/m³), against 24 US AQI (4.3 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
Portland's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| August 2026 | 529.4 µg/m³ | 1,064thof 2,896 | North-western United States and Canada, 4 to 22 August 2026 |
| August 2023 | 447.9 µg/m³ | 1,035thof 1,980 | North-western United States and Canada, August 2023 |
| January 2025 | 437.8 µg/m³ | 1,459thof 2,474 | – |
| November 2023 | 427.6 µg/m³ | 1,269thof 2,243 | – |
| November 2025 | 397.0 µg/m³ | 1,843rdof 2,715 | – |
| January 2026 | 376.7 µg/m³ | 1,901stof 2,617 | – |
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.
Portland's worst days
| Day | US AQI | Episode |
|---|---|---|
| 5 Aug 2026 | 14453.0 µg/m³ | North-western United States and Canada, 4 to 22 August 2026 |
| 4 Aug 2026 | 11440.7 µg/m³ | North-western United States and Canada, 4 to 22 August 2026 |
| 20 Aug 2023 | 10938.6 µg/m³ | North-western United States and Canada, August 2023 |
| 6 Aug 2026 | 8527.1 µg/m³ | North-western United States and Canada, 4 to 22 August 2026 |
| 6 Sept 2024 | 8125.4 µg/m³ | North-western United States and Canada, 4 to 11 September 2024 |
| 9 Nov 2024 | 7421.6 µg/m³ | – |
| 30 Jan 2025 | 7421.2 µg/m³ | – |
| 31 Aug 2026 | 6918.8 µg/m³ | – |
| 2 Feb 2023 | 6818.3 µg/m³ | – |
| 25 Aug 2023 | 6818.0 µg/m³ | North-western United States and Canada, August 2023 |
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, Portland, 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/portland/history (accessed 13 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.
Portland now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-13 00:07 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).