Scientists measure pollution near Caldecott Tunnel

BERKELEY, Calif. (KGO) -- If you drive a big diesel truck through the Caldecott Tunnel over the next week, some official-looking people will be watching you closely.

High above the Caldecott Tunnel, there will be a nondescript white van wired to cameras hidden in the bushes.

A passing trucker may think this will have government sting written all over it. But one look at Chelsea Preble's t-shirt will tell you these aren't spies, they're scientists from the Lawrence Berkeley National Laboratory. "We're out here to measure the emission rates of pollutants from trucks," Lawrence Berkeley National Laboratory Staff Scientist Thomas Kirchstetter said.

They're not just measuring the emission rates of pollutants from trucks in general, they're measuring each individual truck.

There are two cameras by the guard rail. One of them takes a picture and the other reads the license plate. "And the trigger is actually the sensor that's hanging underneath that bush of poison oak," Kirchstetter said.

A third camera will watch the truck's tall tailpipe pass under a tube. All these sensors read the sample and pair it with the license plates. "And the state provides us information about the truck. Namely its engine model year and the types of emission control technology is on board the truck," Kirchstetter said.

California has started requiring even old diesel trucks to have new high-technology exhaust filters. "What we're doing is making an independent on road assessment of how well these emission control technologies are actually doing the job intended," Kirchstetter said.

Though the study is far from over, researchers have already been able to draw some meaningful conclusions. Most importantly, California's new emissions controls seem to be working. "A factor of 10 decrease in the amount of diesel particulate matter that's emitted by those trucks that have a diesel particle filter," UC Berkeley Ph.D. student Chelsea Preble said.

What's more, they can track specific makes and models of trucks as they age. "Just to make sure that the emission control technologies are robust and not deteriorating with time," Kirchstetter said.

It's soot science that could help you breathe a sigh of relief. "Because it's going improve the air quality and improve human health," Preble said.