Bay Area Smoke Thickens, Air Quality Warning Issued Through Thursday

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The Bay Area Air Quality Management District has issued a Spare the Air alert for Wednesday and Thursday as smoke from multiple wildfires burning in far Northern California continues to blanket parts of the Bay Area.

Smoke from the fires in Siskiyou, Trinity and Humboldt counties began creeping into parts of the Bay Area on Tuesday afternoon. By Wednesday morning, air quality in San Francisco, Oakland, Berkeley and San José had reached unhealthy levels, officials said, triggering the air quality alert.

“Yesterday, the impact began around noon over the north bay,” said Duc Nguyen of the Bay Area Air Quality Management District at a press conference Wednesday morning. “As the day progressed, more dense plumes from over the ocean entered the Golden Gate and filtered out across the Bay Area.”

Spare the Air alerts are issued if pollution reaches unhealthy levels. The alert puts into effect a ban on burning wood, manufactured fire logs or other solid fuel indoors and outdoors. It also encourages people to decrease their driving and to protect their health by staying indoors.

During wildfires, air quality officials look for dangerous levels of particulate matter in the air, known as PM2.5. The amount of pollutants and particulate matter is measured on an air quality index, known as the AQI. As of 10 a.m. on Wednesday morning, the AQI for parts of the Bay Area had reached above 150, categorized as “unhealthy” levels.

Health experts are advising people in affected areas to keep outdoor activities short and light, and stay indoors with windows closed if possible. This is especially true for sensitive groups, such as people with heart or lung disease, older adults, children and pregnant people.

Smoke can irritate the eyes and airways. Coughing, a dry scratchy throat and irritated sinuses are common symptoms from overexposure to unhealthy air, and it can trigger wheezing in those who suffer from asthma, emphysema or COPD.

Although smoke was noticeable in many neighborhoods around the Bay Area on Tuesday, air quality officials said they didn’t notify the public earlier because the 24-hour average air quality was at moderate levels, Nguyen said.

“Initially we did not expect to see this amount of smoke,” said Charley Knoderer, manager at the Bay Area Air Quality Management District at the press briefing on Wednesday. “A lot of the models we looked at predicted lower concentrations than what actually came into the Bay Area. So we had to up our forecast.”

Wildfires and smoke are growing more common as changes in climate have impacted soil and foliage, leading to an increase in the intensity, size, severity and duration of wildfires in California and beyond.

Many Bay Area residents remember the “orange sky” day in September 2020, when wildfire smoke was scattered and absorbed by sunlight, creating an orange haze across the region.

Meteorologist Daneil Alrick said the air quality was actually somewhat better back on the orange sky day, however, because much of the smoke was trapped higher in the atmosphere than the smoke creeping into the Bay Area this week.

“In the case of the smoke today, we don’t have that same set up,” Alrick explained. “We have more smoke at the ground level, but it’s not quite as dense and thick as a smoke plume as we had during that [2020] event.”