Air quality warnings that specifically mention children, the elderly and vulnerable people were issued across three states on Labor Day.
Alerts were in place for parts of California, Montana and Idaho until different times on Monday.
In California, a warning has been put in place until 2 p.m. because of elevated particle pollution caused by wildfire smoke. This summer has seen the state plagued with wildfires, which have burnt more than 800,000 acres, killed one civilian and destroyed more than 1,000 structures, according to the California Department of Forestry and Fire Protection’s most recent update.
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The alert covers Riverside, San Bernardino, Ontario, Moreno Valley, Fontana, Rancho Cucamonga, Corona, Idyllwild-Pine Cove, Indio, Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, La Quinta and Coachella.