Is it a law that every house/apartment has to have a carbon monoxide detector as well as a smoke detector? I live in an older apartment complex and am worried that I need to go get my own detector.
Laws on this kind of thing differ not only from country to country but from state to state, so ask your local council.
That said, if you use gas for cooking or for heating, a carbon monoxide detector is a really good idea. It is cheap, the batteries typically last for five or ten years, and it can stop you and your family dying in your sleep!
Get one fitted because you should, not because you have to.