Pool chemicals spilled from a pickup Thursday morning onto Fountain Grove Parkway, creating a large chemical vapor cloud and forcing police to close a stretch of the major route through Santa Rosa during rush hour.

Police had not determined who spilled the muriatic acid and powdered chlorine near Thomas Lake Harris Drive during the morning commute.

It created a traffic mess and major delays for drivers, who crowded connecting streets in an attempt to get around the spill.

One woman who drove through the spill soon after it occurred began complaining of nausea and breathing problems after she arrived at work, said Santa Rosa fire Battalion Chief Jack Piccinini. She was taken by ambulance to a local hospital for evaluation.

Santa Rosa firefighters in lime green haz-mat gear responded to the spill, conducting tests that verified it involved chemicals commonly used to clean swimming pools. Crews then neutralized the residue and removed it, allowing police to reopen the road at about 11:30 a.m.

The liquid and powder chemicals hit Fountain Grove Parkway at about 7:50 a.m., when several one-gallon containers fell off the back of an eastbound pickup as it headed up the hill.

Numerous drivers began calling 911 to report the spill and a growing gas cloud. Witnesses reported a man driving the pickup stopped and began picking up containers and returning them to the back of the truck. But he quickly quit and drove away, appearing to give up as the vapor cloud grew.

The first fire engine to arrive found the intersection obscured by a large chemical cloud, Piccinini said. They also found four unmkarked one-gallon containers on the road, he said.

Chlorine and muriatic acid are a bad combination, especially if mixed in an enclosed area at high concentrations, Piccinini said. Exposure could cause serious respiratory problems.

In the open, exposure still could cause headaches and breathing discomfort for some people, he said.

With reports of a gas cloud, police officers began closing down a large stretch of the road. Fountain Grove Parkway, in north Santa Rosa, is a major route for people traveling crosstown and is busy in the morning and after work.

One Santa Rosa woman headed for work at Medtronic, off Fountain Grove Parkway, said she gave up after about an hour.

"It was ridiculous. I was instructed to go Chanate, Altruria, Bicentennial to get to Medtronic and by the time I got close to the campus, the roads were all blocked," reported the woman, who didn't want to be identified.

"I ended up just going home after an hour of driving around and waiting in the traffic," she said. "It's typically just a 12-minute drive to the office."

Police said the truck most likely belonged to a pool-cleaning company. Witnesses said the white pickup had a business label on the side, but weren't able to give police a name.

It is illegal to spill and run, said Sgt. Mike Lazzarini, who was at the scene as the environmental crime investigations supervisor. The driver should have stayed at the scene or at least contacted police, he said.

"We have to identify who the responsible party is," Lazzarini said. "They are responsible for the cleanup."

You can reach Staff Writer Randi Rossmann at 521-5412 or randi.rossmann@pressdemocrat.com.