Illinois will soon become just the fourth state to require carbon-monoxide detectors in schools.
The law taking effect at the start of the year follows an incident that occurred in Macoupin County in central Illinois where about 150 students and staff members became ill at school.
Many had to be hospitalized due to a furnace leak in 2014.
No detectors were in place at the time, although they have since been installed.
That happened in state Sen. Andy Manar's district.
"I think we have seen enough incidents across the state that warrant this type of legislation," Manar said. "and I think that's why it got so much support."
Manar, a Democrat, says the law requires battery-operated detectors in existing buildings. New buildings must have hard-wired electrical alarms.
