Officials say smoke from a forest fire near Yosemite National Park is affecting air quality in central California.
The San Joaquin Valley Air Pollution Control District urged people with existing respiratory conditions, young children and elderly people to stay in air-conditioned buildings.
District spokesman Anthony Presto said Monday smoke from the fire can cause serious health problems including lung disease, asthma attacks and increased risk of heart attacks and stroke.
The counties affected are Stanislaus, Merced, Madera, Fresno and Tulare.
At Yosemite, visitors could use all trails, campgrounds, lodges and restaurants on Monday.
But Yosemite spokesman Scott Gediman says officials are asking tourists with respiratory issues to be cautious.