SAN FRANCISCO (KRON) — San Francisco Bay Area air quality scientists were caught by surprise this week. Forecast models showed windy weather pushing hazardous smoke from Northern California’s wildfires into the Bay Area. But the volume of smoke blowing into the Bay is far thicker than anticipated, scientists said.

“Wildfires in Northern California and Oregon … have generated a large smoke plume covering the entire Bay Area,” said Duc Nguyen, an air quality meteorologist at Bay Area Air Quality Management District. “The majority of the Bay Area is experiencing unhealthy conditions.”

Overnight, winds continued blowing more wildfire smoke over highly populated cities including San Francisco and San Jose.

Nguyen said, “The smoke is moving down the coastline and entering the Bay Area through the Golden Gate. The brunt of the impact is south of the Golden Gate. North of the Golden Gate, there’s improvement at high elevation areas. Below that, the smoke is pretty much trapped.”

Nguyen said, “We anticipate air quality will be worse today than yesterday, based on a 24-hour average.”

“We have slipped into the orange. It’s pretty nasty. (Smoke) is being literally funneled to us,” KRON4 Meteorologist Kyla Grogan said.

KRON4 Meteorologist Kyla Grogan shows air quality is “unhealthy for sensitive groups” in the East Bay, South Bay, North Bay, and the coast.

The National Weather Service Bay Area wrote, “Updated near surface smoke forecast shows smoke from fires in Northwest California sticking around through Thursday.”

And there’s no end in sight. Nguyen said Friday may see relief from smoky skies, however, it’s still too soon to confirm. “I wish we could answer that, but we cannot,” he told reporters.

The smoke plumes are being generated by wildfires burning near the California-Oregon border, including: Deep Fire, South Fork Complex, SRF Lightning Complex, Happy Camp Complex, and Smith River Complex.

Wildfire behavior is notoriously unpredictable, and Nguyen explained, and there are several important variables shifting the severity of smoke around. For example, smoke traveled a long distance, so timing was difficult to predict.

Nguyen said, “This morning, with current observations, we realized that we need to alert the public and up the forecast to the current conditions, which is actually unhealthy air that folks are breathing right now.”

The current smoke event is especially tricky because smoke is moving south over the ocean before it’s funneled east, from offshore into onshore, said Charley Knoderer, BAAQMD meteorology manager.

Dan Alrick, BAAQMD principal air and meteorological monitoring specialist, said the district has 30 air quality monitoring stations that provide real-time data. But there are no stations positioned out on the ocean.

On Tuesday evening, San Francisco ranked as one of the most polluted major cities in the world, according to IQAir.

How long has it been since the Bay Area had air quality this bad?

Alrick said air quality was worse during a severe wildfire season in September 2020. At the time, several massive wildfires sparked from a rare lightning storm and exploded out of control. September 9, 2020 dubbed “Orange Skies Day” was a climatological event when wildfire smoke created an eerie orange landscape.

Cars drive along the San Francisco Bay Bridge under an orange smoke filled sky on September 9, 2020. (Photo by BRITTANY HOSEA-SMALL /AFP via Getty Images)

Alrick said current wildfire smoke is lower to the ground than to “Orange Skies Day” smoke. The lower smoke plumes hang to the ground, the more hazardous it becomes to people’s health. That’s because your lungs breathe in more smoke when its low to the ground, instead of higher in the marine layer.

“On that day with orange skies … it was orange because there was such a dense plume of smoke. A lot of that smoke was above the marine layer,” Alrick said.

Luckily, current smoke plumes are less thick than in 2020. Air quality is terrible today, but it’s still not as terrible as 2020, Alrick said.

What’s in the smoky air?

Plumes of wildfire smoke are laden with tiny toxic particles called PM2.5.

“No wider than a human hair spliced into 30 strands, PM2.5 can embed deep in the lungs and cross into the bloodstream. Even a few hours or weeks of exposure to elevated levels can trigger asthma attacks, heart attacks, and early death. Longer-term exposure can take months or years off your life expectancy,” Stanford University researchers wrote.

When air quality is unhealthy:

A Spare the Air Alert is in effect. Spare the Air Alerts are issued when ozone or particulate matter pollution is forecast to reach unhealthy levels. If the smell of smoke is present or visible, it is important that Bay Area residents protect their health by avoiding exposure, air quality officials said.

The Bay Area Air Quality Management District gave the following tips for protecting your health while smoke remains in the region:

  • If possible, stay inside with windows and doors closed until smoke levels subside.
  • If temperatures are too hot indoors, visit an air-cooling center or other building that provides filtered air.
  • Set air conditioning units and car vent systems to re-circulate to prevent outside air from moving inside. Smoke can irritate the eyes and airways, causing coughing, a dry scratchy throat and irritated sinuses.
  • Elevated particulate matter in the air can trigger wheezing.