The Idaho Department of Environmental Quality issued an Air Quality Advisory for Ada County and nine other southwest Idaho counties on August 3, 2026, warning residents that wildfire smoke has pushed the Air Quality Index to unhealthy levels across the Treasure Valley region. The advisory, coordinated through the National Weather Service in Boise, remained in effect through 2 PM MDT on Friday, August 4.
Which Counties Are Affected
The advisory covers a broad swath of southwest and central Idaho, including Ada, Adams, Boise, Canyon, Elmore, Gem, Owyhee, Payette, Valley, and Washington Counties. That means communities throughout the Treasure Valley — including Boise, Meridian, Eagle, Kuna, Star, and Garden City — fall under the warning. Residents in all 10 counties are advised to limit outdoor activity, particularly during periods of heaviest smoke.
This latest advisory follows a difficult stretch of summer air quality challenges across the region. Southwest Idaho has been battling heavy smoke drifting in from Oregon wildfires, with conditions expected to remain volatile through the month of August.
Health Risks and Who Is Most Vulnerable
While the unhealthy air quality designation poses risks to all residents, the DEQ specifically flagged children, elderly individuals, and anyone with existing respiratory conditions as being at significantly higher risk for health effects. Symptoms from wildfire smoke exposure can include eye and throat irritation, coughing, and difficulty breathing.
Health officials recommend that sensitive groups remain indoors with windows and doors closed when possible, avoid strenuous outdoor exercise, and use air purifiers with HEPA filters if available. All residents should keep an eye on air quality readings throughout the day, as conditions can shift quickly depending on wind direction and fire behavior.
The DEQ also reminded the public that open burning is prohibited under air quality rules during an active advisory — meaning no backyard burning, agricultural burning, or debris fires are allowed while the advisory is in place.
What Comes Next
The advisory was set to expire at 2 PM MDT on August 4, though residents should monitor conditions closely, as prolonged wildfire activity in the region could prompt additional advisories in the days ahead. DEQ advisories can be extended or reissued if smoke levels remain elevated.
Ada County residents dealing with multiple summer health concerns should also be aware that West Nile Virus has been detected in local mosquitoes this season, adding another layer of outdoor caution to the summer months.
For questions or more information, residents can contact the DEQ Boise Regional Office at (208) 373-0550. Air quality updates are also available through the Idaho DEQ website and the AirNow.gov monitoring platform, which tracks real-time AQI readings across Idaho.