Millions of Americans in parts of Colorado and California were advised to stay indoors Friday as air pollution reached unhealthy levels, exacerbating respiratory conditions. The National Weather Service issued multiple air quality alerts affecting major population centers in both states.
In Colorado, hot temperatures and stagnant weather conditions have contributed to ground-level ozone, often referred to as smog, building near the surface. The Colorado Department of Public Health and Environment issued an Ozone Action Day Alert for the Front Range Urban Corridor, encompassing Douglas, Jefferson, Denver, western Arapahoe, western Adams, Broomfield, Boulder, Larimer, and Weld counties. This alert, which began Thursday afternoon, was expected to remain in effect until 4 p.m. local time Friday. Officials warned that ozone levels could climb into the 'Unhealthy for Sensitive Groups' category. Ground-level ozone forms when sunlight reacts with pollutants from vehicles, industrial facilities, and other sources. Residents were encouraged to reduce driving to limit additional pollution.
The affected area includes millions of residents along the Interstate 25 corridor, from the Denver metropolitan area north toward Fort Collins.
Southern California is facing distinct air quality challenges. The South Coast Air Quality Management District issued an alert for the Coachella Valley, including areas like Indio, Palm Springs, Cathedral City, Palm Desert, La Quinta, and Coachella, due to harmful levels of particle pollution generated by windblown dust. This alert was in effect until 11 a.m. local time Saturday. Additionally, an air quality alert was issued for Boyle Heights and East Los Angeles because of elevated levels of fine particle pollution, known as PM2.5, which remained active until Friday afternoon.
Officials warn that breathing ozone can damage lungs and trigger breathing difficulties, asthma attacks, and other health problems. Fine particle pollution can penetrate deep into the lungs and potentially enter the bloodstream, contributing to serious health issues such as heart attacks, bronchitis, asthma flare-ups, and increased risk of respiratory infections. These pollutants pose greater risks to individuals with heart or lung disease, older adults, pregnant women, children, and those who spend extended periods outdoors.
Residents in the affected regions were advised to limit strenuous outdoor activity, keep windows and doors closed, and utilize air conditioning systems or air purifiers. They were also cautioned against activities that could worsen indoor air quality, such as using fireplaces, candles, incense, grilling, and operating gasoline-powered lawn equipment. Air quality can fluctuate rapidly based on weather patterns and local emissions, and residents were encouraged to monitor local reports and reduce outdoor exertion when pollution levels rise.