California Law requires that all homeowners install a carbon monoxide detector by July 1, 2011. All single-family units intended for human dwelling, with either an attached garage or a fossil-fuel burning source (such as a fireplace), must include a device that has been approved by the State Fire Marshal. All other existing units intended for human dwelling have until January 1, 2013 to install such a device. For information about approved devices, or to learn more about the law, visit the State Fire Marshal website and scroll down to the section on Carbon Monoxide. State Fire Marshal website: http://osfm.fire.ca.gov/strucfireengineer/strucfireengineer_bml.php