Elaine Jones was worried all last year when her sixth-grade daughter Kimberly kept coming home from Riverton Elementary School with chronic headaches.

However, after 18 children were sent to Jordan Valley Hospital with physical problems Tuesday, Jones said she's pulling her other two children from the school.The 18 children's symptoms included rashes, watery eyes, upset stomach and headaches.

On Tuesday, the school called Jones to tell her that her fourth grader, Brooke, was one of the kids having problems.

"Her face swelled up, she had rashes, her fingers swelled and they were stinging and it hurt to breath," said Jones, who personally took her daughter to a pediatrician Tuesday.

The Riverton mother said she's not going to take any more chances with her children's health.

"I'll pick up their homework every day," Jones said. "I can't justify sending them. The risks out-weigh the benefits of going to school right now."

Teachers and students have complained about peculiar odors and various health problems at the school since it opened three years ago. Riverton Elementary is located at 13150 S. 1830 West.

Theories abound about what causes the mysterious troubles. They range from sick building syndrome to possible exposure to hydrogen sulfide, which can come from sewer gas.

But so far, there has been no official identification of what the problem is or what causes it.

Children had complained of rashes on Monday, then troubles began appearing early on Tuesday with more student complaints.

By about noon, the Salt Lake County Fire Department's hazardous materials unit and the county Health Department had arrived at the school to test the air but were unable to determine a specific cause of the problems.

"Our crews haven't found anything. This problem becomes apparent when the weather goes bad," said Salt Lake County Fire Capt. Bill Brass.

This wasn't the first time the building's air quality had been tested.

Melinda Rock, Jordan School District spokeswoman, said Riverton Elementary has been tested more than any of the district's 72 schools.

"We as a district have hired health officials, environmental and safety professionals, sewer district officials, engineers, scientists and national experts," she said. "They came in, they conducted every study possible. They found nothing.

"One of the experts said it's one of the cleanest buildings he has ever tested," Rock added.

Many parents were furious that the school was not evacuated until after about 2:30 p.m. Students were put on buses and waited for about an hour for the end of the school day.

Rock said transporting them to another school in the bad weather didn't make sense because by the time they arrived at another school it would be dismissal time, and they would have to come back.

"Please don't think I'm downplaying this. We would not have kept the students in the school if we ever felt they were in any danger," she added.

Rock said the district will continue to monitor the school.

That still doesn't make Debra Johanson very happy. She speculates that gases from a nearby sewer have been backing up into the school.

The sixth grade wing has been especially hart hit, she said, but the problem appears to be spreading.

Another parent, Dorothy Dearden, said it was ironic that Tuesday's hospitalizations occurred the same day parents got a letter from school officials "saying everything is OK."

She said she personally experienced respiratory problems and lost her voice while doing volunteer work at the school. All symptoms eventually subsided after she left the building.

Unlike many parents who angrily accused the district of trying to cover up the problem, Dearden said she appreciates the efforts being made.

"They are really trying. They've done lots of tests," she said.

Still, Dearden is worried, not only for her own children, but those of friends who have experienced severe asthmatic reactions during winter, which is unusual for those youngsters.

For her part, Jones' experiences with school officials have been mixed.

"Superintendent Barry Newbold has been wonderful to work with, but the in-between people have been difficult," she said.

Jones said she's especially disturbed at reports that some school officials have accused children of faking, succumbing to mass hysteria or copying each other.

"I don't believe it. How do children copy-cat a rash?" she asked. "I don't care what their meters read. If you still have sick people, you still have a problem."