The North Bay will see hazy skies for the next several days due to smoke from the Pickett Fire burning in Napa County near Calistoga, air quality officials said Monday.

The Bay Area Air District extended its air quality advisory through Wednesday as the smoke from the firm is expected to continue impacting Napa, Solano and Sonoma counties. It is the third time the advisory has been extended since the Pickett Fire began on August 21.

The fire burning north of Calistoga has burned about 6,800 acres, or about 10.6 square miles, with containment at 13% as of 10 a.m. Monday. While no structures have burned, 615 structures were threatened, according to Cal Fire. 

The cause was still under investigation.

The Air District said exposure to wildfire smoke is unhealthy even for short periods of time, and residents should stay indoors with windows and doors closed until smoke levels subside. 

Pollution levels were not expected to exceed the national 24-hour health standard, and a Spare the Air Alert was not in effect, the Air District said.

Resident can check their air quality at fire.airnow.gov and learn how to protect their health from smoke at baaqmd.gov/wildfiresafety.