The Environmental Protection Agency says students at three North Texas schools are breathing dangerous levels of toxic chemicals.
A study by USA Today and the EPA tested the impact of industrial emissions outside more than 127,000 schools across the country.
Parents said they were shocked to learn some schools had toxic chemicals in the air.
"Well, it's kind of scary, because I got my daughter and my niece going to school," parent Rosie Camacho said.
Her daughter is 6 years old and attends Saldivar Elementary School.
The EPA said it conducted the study because children are more susceptible to the dangers of toxic chemicals in the air.
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Chromium 6, which the EPA says can cause liver and kidney damage and cancer, was among the chemicals found in the air near Saldivar Elementary.
The EPA said diisocyanates emitted by nearby Western Extrusions were found lingering in the air near A Child's Garden Montesorri School.
The school declined to comment.
A Western Extrusions spokesman said diisocyanates were used for a residential product that is no longer being produced. The emissions of it will be minimal in 2008, he said.
The superintendent of Midlothian Independent School District said there are no concerns about the air quality. The superintendent said the Texas Commission on Environmental Quality monitors the air quality within the city, especially near parks and schools.