Downtown Sacramento was engulfed in a brown haze for much of Tuesday, which air quality management officials attributed to dust blowing in from the region's farms.
High winds exacerbated the situation, with gusts reaching 40 mph at Sacramento International Airport, the National Weather Service reported.
"Farmers are tilling their fields. This dust is from all over Northern California," said Christina Ragsdale, spokeswoman for the Sacramento Metropolitan Air Quality Management District.
Despite the thick haze, district officials insisted the air was perfectly healthy to breathe. At 2 p.m., the air quality index for downtown Sacramento registered 55 for particulate matter, which is considered "moderate" and five points above normal.
Still, without testing the particles, it would be nearly impossible to determine their origin and safety, said Anthony Wexler, director of the Air Quality Research Center at the University of California, Davis.
"Is dust hazardous to human health? It depends on what's on it, if farmers are using herbicides or pesticides," Wexler said. "That stuff can be very toxic."
The high winds are expected to continue today, with gusts up to 25 mph. Tonight is the "earliest the air will clear up," said weather service forecaster Drew Peterson.
"All you need is one strong gust of wind, and it will pick up a lot of debris," Peterson said. "It's instantaneous, more or less."
The winds, blowing north to south, are also creating potentially hazardous driving conditions along major thoroughfares, including Interstate 80 and Highway 50.
Motorists traveling on I-80 between Dixon and Davis reported seeing unusual amounts of dust in the air, though visibility wasn't affected, according to Tom Hall of the Yolo-Solano Air Quality Management District.
The wind and dust forced many area residents to reach for inhalers and allergy medications.
"My secret is start your medicine early," said Sonya McPhaul, 50, a longtime allergy sufferer. "I don't wait until I get sick."
McPhaul, who was walking outside a Natomas strip mall Tuesday, said she's allergic to tree pollen and doesn't ever venture outdoors without a pack of three inhalers.
"It's very heavy duty," she said.
Dr. NaYoung Kim, an allergist at Kaiser Permanente in Sacramento, noted that combating allergies requires a "multi-pronged" approach, depending on a patient's needs.
For starters, Kim recommends staying indoors and taking over-the-counter medicines during high-allergen days.
"There's no easy answer. Not everyone's allergies are the same," Kim said.
Call The Bee's Richard Chang, (916) 321-1018. Follow him on Twitter @RichardYChang.