I receive a monthly newsletter from a home inspector I recommend quite a bit.  His name is Peter Ottowitz and Peter is a licensed home, mold and energy inspector. 
I enjoy reading his e-newsletter because there is always a tidbit of information I get from it which I was not previously aware.
This month, the featured article was on a silent killer we normally hear about in the winter months, and that is carbon monoxide.  You may remember there was a lot of press about it a few years ago.  The law was passed in MA, and made effective in March, 2006 that made it mandatory for all homes to have monoxide detectors installed.  The statistic quoted by the Home Safety Council that blew me away is that currently, only about 35% of homeowners have carbon detectors in their home.  

I thought I would share with you exactly how easy, and inexpensive it is to install a CO2 detector.  The law states that for existing homes, the detectors do not have to be hard wired.    So, first, go to your local hardware or home improvement store.  Ask for a plug in model of the detector.  
The cost runs between $30-50 for each detector (in some areas they may be more or less).  Some come with batteries.  I can tell you from experience, these batteries are not always functional.  Having a CO2 detector will do you no good if the batteries are not working.  To be on the safe side, just purchase some additional 9V batteries.  If the ones provided are working, you will have extra on hand when the annoying chirping sound starts indicating the batteries need to be replaced. 

The law calls for 1 detector for each level in your home.  Yes, that does include the basement, regardless of if it is finished or unfinished.  The law also states that one detector is needed to be within 10 feet of the bedrooms.   So, if you have a colonial or cape, for example, you would need  minimum of 3.....one for the basement, 1st floor and 2nd floor.  If the bedrooms in your home are spread apart, you may need 2 for the level the bedrooms are located.  
Remove the detectors from their packaging, and plug them into the wall.  If you hear an annoying chirping sound that does not stop, then you will be happy you purchased additional batteries as back up. 
And that's it. 

You are absolutely required to have CO2 detectors in place before selling your home.  I urge you to go to the store today to purchase these life saving devices, install them and protect you and your family from the silent killer known as carbon monoxide poisoning.