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SACRAMENTO, Calif. (KTXL) – The Sacramento area has seen unhealthy air before, often blown in from far away wildfires, but there was no hint of smoke Friday, with northerly winds blowing wildfire smoke away from the region. 

“It’s very nice,” said Lorraine Richards. 

Richards, who was at the park with friends, knows what a bad air day can look like during fire season.

“I would put my mask on and get out of the outside,” Richards said. 

“The sky looks so blue so you think there’s really no problem. But ground-level ozone is invisible,” said Jamie Arno, with Sacramento Metro Air District. 

Because ozone pollution is not visible, many people feel it’s safe to be outdoors on a day like Friday. 

“I wasn’t totally aware of that,” said Malcom Richards. 

Richards runs every day — rain or shine. But he did not know Friday was a Spare the Air day because he did not see smoke. 

“When the fires are bad, I’ll usually check the air quality then, but I don’t get in the habit of doing it on other days,” Richards said. 

Climate change may make Spare the Air days more common. Heat and no wind allow auto emissions to cook under inversion layers.

“It may get worse before it gets better,” said Anthony Wexler. 

Wexler directs the Air Quality Research Center at UC Davis. He says warmer climates can concentrate ozone levels. 

“The higher the temperature, the more solar radiation beating down, the more the photochemistry occurs that creates the ozone,” Wexler said. 

Wexler believes electric vehicles can turn the tide eventually, but climate change will still make wildfires more common. Spare the Air days can be harmful to people like the elderly, those with breathing issues and small children. 

But the highest ozone levels occur between 2 p.m. to around 7 p.m., meaning there is room for outdoor time if it’s a must. 

“If you typically do it before noon, ozone levels are typically OK,” Arno said. 

Last year, there was just one Spare the Air day. Pollution officials say that was because fewer people were driving and auto emissions were greatly reduced.