Parents are sneaking carbon dioxide monitors into their children’s schools to determine whether the buildings are safe.

Bean backpack with pencils, wide-ruled paper — and a portable carbon dioxide monitor.

Low levels of CO2 would indicate that it was well-ventilated, reducing her son’s odds of catching the coronavirus.

“Ideally there’d be some machine that cost $100 and it starts beeping if the virus is in the air,” said Jose-Luis Jimenez, an aerosol scientist at the University of Colorado Boulder, who is sending a carbon dioxide monitor to school with his son.

Louis area, said that she bought her monitor after losing confidence in officials in her son’s school district.

recommends that indoor carbon dioxide levels remain below 800 p.p.m.

After Shanon Kerr, of Waterloo, Canada, found high CO2 levels in some of her daughter’s school spaces, she asked district officials to monitor indoor air quality throughout the building, even offering up her own CO2 monitor.

Kerr identified revealed that carbon dioxide levels “were within acceptable parameters.”.

Kris Munro, the superintendent of Santa Cruz City Schools, said she is confident in the ventilation upgrades the district performed last winter and that it would be inappropriate to put individual students in the position of monitoring school air quality.

But the monitors did capture a small spike, when CO2 rose above 900 p.p.m., during a lockdown drill at his son’s middle school, when the teacher closed the classroom door.

And high-quality air filters can trap viral aerosols, but have no effect on carbon dioxide levels

But even in the absence of the virus, reducing indoor carbon dioxide levels can have benefits

Of course, many families cannot afford a $100 air quality monitor — and they should not have to, parents and scientists said

Chrysler, whose CO2 readings prompted his Arkansas district to repair its HVAC system, is now lobbying officials to buy air quality monitors for every classroom in the district

Jimenez said he would like all public indoor spaces to provide permanent real-time displays of the carbon dioxide levels: “This is something that we should do permanently in schools but also in all places where we share air.”