According to the National Conference of State Legislatures, only two states have laws requiring carbon monoxide monitors in schools.

Yet, a recent gas leak at a Utah elementary school sickened more than 40 people, and last December, 49 people were treated for CO poisoning after exposure at an Atlanta elementary school. At the time, USA Today reported that since 2007, there were at least 19 cases of high CO levels at schools, resulting in evacuations of more than 3,000 students and hospitalizations of 349 children and school staff members. Since last November, at least five more U.S. schools reported CO leaks, according to AP.

Lawmakers in several states are considering legislation to equip classrooms with carbon monoxide detectors, including Georgia, Ohio and Pennsylvania. Carbon monoxide detectors are more typically used in residences where people sleep. The National Conference of State Legislatures reports that 25 states have statutes requiring them in certain residential buildings.

A story about putting CO detectors into schools at estimated the cost of individual CO detectors at $40 apiece. Every classroom would need one, because each enclosed space requires its own unit.

Utah’s San Juan School District, where the most recent school CO poisonings happened, is considering installing CO detectors in its classrooms, The Deseret News reported.