Don't Overlook California CO Detectors

Carbon monoxide is colorless, odorless and toxic. It's called the "silent killer" in homes because some victims are not even aware that the deadly condition exists.
In California, detectors must be installed:

(1) For all existing single-family dwelling units on or before July 1, 2011.
(2) For all other existing dwelling units on or before Jan. 1, 2013.

Where should they be placed?  For minimum security, a CO detector should be centrally located outside of each separate sleeping area in the immediate vicinity of the bedrooms, and  should be located at least 6 inches from all exterior walls and at least 3 feet from supply or return vents. I have even heard that during escrow, some appraisers will "call out" a missing detector on their appraisal. If you're a homeowner or landlord, don't wait to comply with this requirement now.
Property owners must be concerned about unmaintained furnaces, water heaters and appliances that can produce the deadly gas. Other sources could include leaking chimneys, unvented kerosene or gas space heaters and even exhaust from cars operating in an attached garage.
The Environmental Protection Agency suggests the following to reduce exposure in the home:

• Keep gas appliances properly adjusted
• Install and use an exhaust fan vented to the outdoors over gas stoves
• Open flues when fireplaces are in use
• Do not idle your car inside a garage
• Have a trained professional inspect, clean and tune-up central heating systems annually

Lower levels of carbon monoxide poisoning can be mistaken for the flu.

It's also possible to buy them in combination with a smoke alarm. Read more at HouseLogic.