Tests conducted inside four brand-new portable classrooms at an elementary school showed no dangerous levels of toxins, Capistrano Unified School District officials told parents this week.
The buildings at Carl H. Hankey Elementary School were tested after two students suffered seizures and other students felt ill last month.
Some parents feared the illnesses could be linked to toxins.
"The problem could have been related to proper airflow," said Dr. Joseph Fedoruk of UC Irvine's School of Medicine, who conducted comprehensive tests for a variety of volatile organic compounds.
"It's not like there's a toxic bogyman inside the rooms that's going to harm the children somewhere down the road," Fedoruk said. "The rooms have been tested and we have some pretty good assurances of what we're dealing with."
At a special meeting, officials told the parents there was no evidence linking the portable classrooms to the seizures and that one of the students had previously suffered seizures.
But Susan Rafla, the mother of the other child who suffered a seizure, said she has still been unable to "rule in or rule out" the possibility that the portable building could be linked to her daughter's episode.
"There's no history of epilepsy in our family," said Rafla, whose daughter has been moved to another classroom. "They really don't know what causes seizures in many cases, so there's still a question in my mind."
Most parents at the meeting said they were satisfied with the district's efforts to solve the problem. "There has been some benefit if not for our children then certainly for other children who are placed in portables in the future," said parent Diane Hummel. "I think parents appreciate the honesty."
Poor ventilation has been pinpointed as the problem: It was discovered that valves inside the air-intake systems of two buildings, which allow outside air to enter the rooms, were closed and may have restricted airflow, said William D. Eller, associate superintendent.
The district is seeking ways to enhance ventilation, and is also developing guidelines for "outgassing," a procedure for new portable classrooms that accelerates the natural release of gases found in products such as plywood, Eller said.