Starting Sunday, a new law in Maryland will require carbon monoxide alarms to be installed in every room of rental units.

Two years ago, Maryland‘s General Assembly passed this law that requires carbon monoxide detectors to be in all bedrooms of apartments and rental units starting April 1st, this year.

Officials recommend that hardwired smoke alarms should be replaced with a combination smoke alarm and carbon monoxide unit. Alarms are also required to have a ten-year battery with a seal.

“You can’t smell it, you can’t see it, so it’s often called, ‘the silent killer,’ because it’s hard to detect,” said Montgomery County Fire and Rescue spokesperson, Pete Piringer.

Carbon monoxide is an odorless, colorless gas, which can cause sudden illness and death.