August 6, 2026
Air Quality Update | August 6, 2026 | 2 min read
Portland has climbed from the world's 10th-worst air quality to the very top of the global rankings in less than a week, as wildfire smoke settles over the Willamette Valley. Here's what's driving it and how long it's expected to last.
Portland's air quality index reached 159 this week, placing it in the "unhealthy" category and, at times, ranking it as the single worst major city in the world for air pollution — worse than Delhi and Kuwait City. The city first appeared in the global top 10 on August 3, then climbed to the top spot by August 6, according to IQAir, which tracks air quality in roughly 120 major cities worldwide.
A shift in wind direction is the main driver. Winds turned from west to northeast and then easterly, carrying smoke from fires in eastern Oregon and central Washington across the Cascades and into the Willamette Valley. The closest major contributor is the Grasshopper Fire, burning roughly 34,000 acres near Mount Hood and moving into Clackamas County, putting Portland and Vancouver, Washington directly in its path. A heat pattern trapping smoke near the ground is compounding the problem.
This is happening against the backdrop of a historic fire season. Oregon has now burned more than 2 million acres in a single year for the first time on record, and roughly 2 million acres have burned across the Pacific Northwest overall. For comparison, Portland's average PM2.5 level in 2025 was low enough to rank as "good" air quality — a sign of how far outside the norm this week's smoke event is.
Oregon's Department of Environmental Quality has an air quality advisory in effect for much of the state through Thursday evening. Forecasters expect a marine push of westerly wind off the ocean to begin clearing smoke over western Oregon starting Thursday, with noticeably cleaner air likely by Friday.
Prep your home while smoke lingers
Closed doors and windows help, but smoke particles still work their way inside. A few steps to take now:
Sources: IQAir, OPB, KOIN, Oregon Department of Environmental Quality.
