It happened around 12:30 Thursday afternoon at Ericson Elementary School.
Authorities say dozens of kids were on the playground during the lunch recess, when they began complaining of nausea and vomiting.
A hazmat crew was called out.
Firefighters determined a company was resurfacing a pool just west of campus. They say the chemicals in the air can be irritating and mildly toxic when inhaled.
The odors were cleared within about an hour and students were allowed to stay on campus until school let out.