You can't see it, taste it, or smell it, but it can be there when you least expect it. Carbon Monoxide -- and it's a killer. As of July 1st 2011, all single family homes are required to have alarms installed outside of every bedroom and on every floor of the home. Gov. Arnold Schwarzenegger signed this into California Law. They are easily purchased at any hardware store. More info at firstalert.com.