The message coming from the San Joaquin Valley Air Pollution Control District on Monday was deadly serious.
They spoke as if your life might depend on it.
"We have fires to the north of us, to the south of us, the east and the west, so the challenge we've had is it doesn't really matter which way the wind is blowing. The smoke continues to come into the San Joaquin Valley," said Jon Klassen, director of air quality science and planning for the air district.
And because the valley's topography is shaped like a bowl, smoke is often trapped here once it arrives.
Klassen and other air district officials updated reporters and took questions at a remote-video briefing held Monday from their offices in Fresno. They described an unprecedented wildfire season that has consumed a record 3.2 million acres, leading to hazardous wildfire smoke impacts in all valley counties.
In recent days, the sky has looked a lot like a typical overcast winter day in the valley. But don't be fooled by appearances, Klassen said. Although winter days can have poor air quality, there is no similarity to the current problem.
"I just wanted to be clear," he said. "That's definitely not anywhere near what we're seeing here and over the past few weeks."
Dangerous, microscopic PM 2.5 particulate pollution, normally a wintertime problem, is being carried into the valley with the smoke in high concentrations.
Typically in the winter, concentrations of PM 2.5 get up to about 65 micrograms per cubic meter.
"We're seeing double that, or almost triple that in some of our readings," Klassen said. "So these are very, very high concentrations."
Most of these mega-readings have been in the Fresno-Madera area, due to their proximity to some active fires.
The entire valley is seeing poor air quality, but Bakersfield and other south valley communities aren't being inundated as badly as Fresno.
"Bakersfield is a little bit better than the rest of the valley," he said.
The east side of the valley could see some improvement by Thursday and Friday as winds are expected to shift toward the end of the week. But conditions can change rapidly.
What can we do about it?
"First and foremost, our message has been and continues to be stay inside," said Jaime Holt, the air district's chief communications officer.
Holt acknowledged that people are "sick and tired" of being inside for the past six months as residents have sheltered in place in response to the coronavirus pandemic. But in this crisis, staying indoors as much as possible is the best choice.
Officials are advising people to change the filters on their air conditioners every two or three weeks rather than every two or three months.
Investing in air purifiers is also advised, she said.
"We also have witnessed a lot of people doing activities outside, exercising or jogging," Holt said.
The district's "No. 1 advice" is to avoid cardiovascular exertion — vigorous exercise — during episodes when wildfire smoke is evident.
Individuals who work outdoors should talk with their supervisors or human resources managers. If arrangements cannot be made to avoid outdoor work, employers are required to supply workers with an N95 mask.
Cloth masks and regular paper masks are not effective in keeping out such high concentrations of wood smoke, Holt said.
Children and older people are particularly at risk, she said. And great effort should be made to protect them from these dangerous levels of PM2.5 and larger smoke and ash particulates.
Five of the 20 largest fires in the state's history have occurred in 2020, Klassen said. And wildfire season is far from finished. This is not over.