The chance of smoke from wildfires in Northern California and Oregon working its way on the wind down to the Bay Area prompted the Bay Area Air Quality Management District to call for an air quality advisory through Sunday.
Similar advisories have been in effect since Wednesday, district spokesman Ralph Borrmann said.
It isn't known where, or if, smoke could become a health concern, as that is largely based on wind patterns that have yet to develop.
There was a light smoky haze over parts of the Bay Area today, but Borrmann said that doesn't present a health concern. More smoke, and smoke closer to ground level, could become more of an issue, he said.
"We're not getting exceedances of federal health standards - the smoke is higher aloft, not at ground level where our monitors would pick it up," Borrmann said.
Barring a major influx of such smoke, Bay Area air quality is expected to remain in the "moderate" range, and no "Spare the Air" alert is expected to be called, Borrmann said.