Programming note: For more about environmental health issues in the classroom, watch Dr. Sanjay Gupta's report "Toxic Schools" on "CNN Presents" this Saturday and Sunday at 8 p.m. and 11 p.m. ET on CNN.
(CNN) - As a third-grader in Winsted, Connecticut, last year, Matthew Asselin was sick - a lot. He was lethargic and plagued with a persistent wet cough, respiratory infections and painful headaches.
As the school year wound down, Matthew's health worsened. He was out for two weeks in the spring with pneumonia and then developed a sinus infection so severe he needed to spend the night at the hospital, where he received intravenous antibiotics and breathing treatments.
In all, Matthew missed 53 days of school.
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But over the summer, a strange thing happened. Matthew was healthy. He was energetic. He could ride his bike for hours at a time.
"When we put him back in school this year, within three weeks, he missed 10 days with a respiratory infection," Melissa Asselin said. That's when Matthew's mother had an a-ha moment.
"When he was out of school, he was well. When he was in school, he became ill," Asselin said.FULL STORY