Smoke from wildfires in the Sierra Nevada will continue to affect air quality in foothill and mountain communities through the weekend and remain on the Valley floor, local air officials said.

A health caution issued this week has been extended through Sunday.

“We urge Valley residents to take note of their local air quality conditions and take precautions as needed,” said Jaime Holt, the Valley Air District’s chief communications officer.

For the past several days, the French, Dark Hole and El Portal fires have sent smoke to foothill and mountain communities in Merced, Madera, Fresno, Kings, Tulare and Kern counties and to the Valley floor. New fires have also started in northern California.

Smoke from wildfires contains particulates and ozone precursors. Residents are urged to be aware of their local conditions. People with existing respiratory conditions, young children and elderly people are especially susceptible to health effects from these pollutants. Air District officials urge residents to follow their doctors’ orders when exposed to wildfire emissions.

Residents can check the District’s wildfire page — www.valleyair.org/wildfires — for information about any current wildfires and whether they are impacting the Valley. The District also provides the Real-time Air Advisory Network (RAAN), an automated reporting system that delivers data directly to users’ computers. It’s free and easy to subscribe! Visit http://www.valleyair.org/RAAN for complete instructions.