Is the air quality good in the western US?
As of July 21, 2026, air quality across a broad swath of the western United States has deteriorated sharply, with PM2.5 as the dominant pollutant driven by smoke from nearby active wildfires (1).
By 10:30 PM (local time, GMT-6), some urban centers have recorded AQI readings between 100 and 200, reaching unhealthy levels and prompting health warnings.
Residents are advised to limit outdoor activity, keep windows and doors sealed, wear a mask if going outside is unavoidable, and run air purifiers indoors.
Air quality map of western US, as of 10:30 PM (GMT-6) on July 21, 2026. Source: IQAir.
Which cities are affected by bad air quality in the western US?
As of July 21, 2026, the following cities in the western United States are experiencing poor air quality:
Air quality conditions can change rapidly throughout the day. For a complete, real-time overview of pollution levels, see the United States air quality map.
Portland and Salt Lake City ranked among the world's most polluted major cities as of 10:30 PM (GMT-6) on July 21, 2026. Source: IQAir.
When will the air quality improve in the western US?
Air quality is expected to improve gradually later this week as temperatures ease and weather conditions become more favorable (2). However, intermittent smoke episodes may continue as long as active wildfires remain burning across the region.
What is causing poor air quality in the western US?
Poor air quality is being caused by smoke from multiple active wildfires burning across Oregon (3). Hot, dry, and windy conditions are intensifying the fires and carrying dense smoke into major population centers.
How can I protect myself from poor air quality?
- Get a free air quality app for real-time air quality alerts and forecasts.
- Shut doors and windows and set the HVAC to recirculate mode.
- Contribute to your community’s outdoor air quality data.
- Stay indoors when air quality is poor; if you do need to go outdoors, wear a KN95/FFP2 mask.
- Run a high-performance air purifier to filter particles, gases, and other pollutants.
