Air quality alerts have been issued across five Western U.S. states, urging residents to stay indoors as wildfire smoke and ground-level ozone threaten to push pollution to unhealthy levels. The National Weather Service (NWS) issued these alerts on Thursday.
In the Pacific Northwest, wildfire smoke is expected to cause elevated pollution across parts of Oregon, Washington, and Idaho. Smoke alerts for these states are set to remain in effect through Friday, with some areas potentially experiencing hazardous conditions. Residents in these regions are advised to remain inside if possible, close windows and doors, avoid strenuous exercise, and utilize air purifiers.
Farther south, harmful concentrations of ground-level ozone are a concern for communities surrounding Phoenix and Tucson, Arizona, as well as Southern California. Arizona's advisories cover the Phoenix and Tucson metropolitan areas through Friday evening. The South Coast Air Quality Management District in California issued an alert for harmful ozone pollution across the South Coast Air Basin and Coachella Valley, including communities in the Inland Empire, San Bernardino and Riverside County valleys, Orange County, and the San Gorgonio Pass. This ozone alert in California is expected to last until Monday evening.
Officials are urging residents to limit outdoor activity. When pollution levels are high, children should be kept indoors, and windows and doors should be closed. Both wildfire smoke and smog contain fine particulate matter, or PM2.5, which are microscopic soot particles that can penetrate deep into the lungs and bloodstream, potentially worsening respiratory and cardiovascular conditions. Breathing polluted air can cause immediate symptoms such as burning eyes, a runny nose, and difficulty breathing. Wildfire smoke can also aggravate existing heart and lung diseases. Vulnerable populations, including infants, young children, older adults, pregnant women, and individuals with asthma or existing heart and lung conditions, face the greatest risks.
Ozone pollution, in particular, can trigger asthma attacks, cause breathing problems, and damage lung tissue. While these groups are most susceptible, officials cautioned that everyone can experience health effects when air quality deteriorates to unhealthy levels. The severity of recommended precautions depends on the Air Quality Index (AQI). At the 'Unhealthy for Sensitive Groups' level, vulnerable residents should reduce prolonged or intense outdoor activity. At 'Unhealthy' levels, sensitive individuals should avoid extended time outdoors, and everyone may begin to experience health effects. If air quality reaches 'Very Unhealthy,' vulnerable people should avoid all outdoor exercise, while others should limit strenuous activity. At the 'Hazardous' level, all outdoor physical activity should be avoided by everyone.
In California, residents were advised to keep windows and doors closed and to run air conditioners or air purifiers to maintain indoor air quality. Using whole-house fans or swamp coolers that draw in outside air was discouraged, as was creating additional indoor pollution by burning candles, incense, using fireplaces, or grilling.
Arizona's Department of Environmental Quality issued an Ozone High Pollution Advisory for the Tucson metropolitan area from Friday morning through Friday evening, including Tucson, Green Valley, Maricopa County, and the Phoenix metropolitan area. Officials encouraged reducing physical activity, delaying the use of gasoline-powered equipment, telecommuting, carpooling, or using public transportation to help mitigate pollution.
In Idaho, unhealthy air is forecast for Ada, Canyon, Gem, Payette, and Washington counties until Friday afternoon. The NWS advised everyone in the affected area to limit prolonged or strenuous outdoor activity, with sensitive individuals urged to avoid smoke altogether. Open burning is also prohibited under local air quality rules.
Washington's warnings cover large parts of the eastern portion of the state, including Spokane, Pullman, Wenatchee, and Walla Walla. Pollution is expected to range from 'Unhealthy for Sensitive Groups' to 'Unhealthy.' The most critical conditions are anticipated in eastern Okanogan County, near active wildfires, where air quality could potentially reach 'Very Unhealthy' or 'Hazardous' levels. Officials in all affected areas stressed the importance of reducing exposure, limiting time outdoors, and avoiding strenuous activity until air quality improves.