We know smog from the Bay Area blows into the Valley, but researchers are discovering the dirty air may be coming from more exotic locations as well.
There's no doubt most of the Valley's air pollution is home grown, but enough may be coming from as far away as China to hurt local efforts to clear the air.
This specially equipped plane is taking to the skies to find out what's in the air you breathe. Pilot Steve Conley is also an atmospheric scientist.
The air comes in through special tubes and is instantly analyzed on by an onboard computer. It will help scientists with the San Joaquin Valley Air Pollution District figure out how much harmful ozone is in the air, and even, where it's coming from. It's believed some of our dirty air is blowing in all the way from Asia.
"What we're talking about is a category now that's increasingly important about what's happening on the ground here in the Valley - it's called trans-boundary ozone," San Joaquin Valley Air Pollution District Health Advisor David Lighthall said.
Ozone is formed when the chemicals in smoke and organic compounds are heated by the sun, becoming toxic and hazardous to health. The Valley Air District has been fighting to reduce levels of ozone produced in the Valley but believes 10 or 15 percent came from places beyond their control.
"We can't stop the overseas pollution but we want our policy makers our lawmakers, our folks in Sacramento and Washington D.C. to understand that some of the pollution that is keeping us from reaching our goals isn't coming from the Valley," Jaime Holt of the San Joaquin Valley Air Pollution District said.
That's important because Valley residents are already being penalized with higher vehicle registration fees because of higher than allowed pollution levels.
The equipment in the plane is so sensitive that flying over Valley ranches and dairies the sensors also pick up a local pollution source.
But scientists aren't tracking that, but they are looking for the stuff that blows in from elsewhere. The air samples collected are shipped off to scientists who can figure out if they came from a coal burning plant in China, car exhaust from the Bay Area or cows in Tulare County.