The sixth-grade wing of ailing Riverton Elementary School was shut down Thursday, but the rest of the three-year-old school is open for business.

A number of parents Wednesday night demanded the school be vacated until officials can determine why students are occasionally sickened in the building.Eighteen students were taken to the hospital Tuesday afternoon after complaining of headaches, nausea, rashes and other physical ailments. The remainder of the 750 students were evacuated.

Jordan School District Superintendent Barry L. Newbold and other district officials met with about 300 parents in a hastily called meeting at the school Wednesday night.

Newbold told the parents he would shut down the sixth-grade wing at Riverton, the area most often affected by what victims describe as a peculiar smell followed by the onset of illness.

Thursday morning, district officials said that the sixth-grade area had been sealed off, with students moved to other parts of the building.

Melinda Rock, district spokeswoman, said district administrators met Thursday morning to review parents' suggestions and recommendations. The district will then map out the next steps to be taken, she said.

Meanwhile, district administrators were to present their recommendations to the Jordan Board of Education during an emergency meeting at 3 p.m. Thursday in the district office, 9361 S. 300 East, Sandy.

Wednesday, Newbold and Robert Day, assistant superintendent of auxiliary services, said they weren't sure what the problem is but have expended a lot of energy and resources, including hiring outside environmental firms, to find it.

The district mailed a two-page letter to parents this week listing changes made in the building over the past months and saying it believes the problem has been "isolated." One parent pointed out the irony of receiving the letter the same day she went to the hospital to pick up her daughter after being treated.

Day said a fixture required on the kitchen drain system in new buildings and being retrofitted onto older structures may be the source of hydrogen sulfide, or sewer gas.

Steps have been taken to mitigate the problem, Newbold said, but until the school operates as usual while air quality monitors sniff for emissions, they won't know if the problem is fixed - or even if that is the trouble source.

Two other schools in the district fitted with the fixture have had problems, Day said, but 13 other buildings similarly altered have had no problem.

Air monitoring tests done in the school by private and government environmental agencies show no sign of contamination and no health risk, the letter stated.

Newbold said the sixth-graders can temporarily be moved into the school's media center and gym but that is not a solution, and vacating the building is not an option.

"It's a starting point," Newbold said of moving the sixth-graders. Newbold said he can't shut the building down on his own authority, and the school board Tuesday decided that unless continued monitoring detects a definable hazard, the building will stay open.

You will have to make the decision to send your children back or not, Newbold told the sometimes raucous group, adding he would not hesitate to send his own children or grandchildren back into the school.

Newbold and principal Bonnie Dahl were mildly critical of the response of the volunteer Riverton Fire Department and the Salt Lake County department, which also responded Tuesday afternoon.

"It was frightening for the students," Newbold said. "They were having difficulty breathing; others had redness and swelling.

"That in itself is alarming. Then you have the firetrucks and ambulances rolling up, the firemen coming in the halls with their masks and breathing apparatus on and ordering the school evacuated.

"It was very frightening to the students. It was just not a good solution," said Newbold. "There could have been better communication between all of the parties involved."