In your Nov. 2010 issue, on page 16(Home Solutions), there is a mistake referencing carbon monoxide(CO) "doesn't rise like smoke, CO detectors don't need to sit high on the wall. Instead plug one into a socket ..." This is something that needs to be corrected.
CO has a vapor density of 0.97, meaning that it is lighter than air and will rise. This is why CO detectors need to be at high locations in garages and around appliances that use gas as a source of combustion. CO is known as the "silent killer" and by the time your detector 18" off the ground goes off, the levels 6' high could be near the lethal limit. As low as 8 ppm over 24 hours, or 35 ppm over 8 hours, can cause a healthy adult to become symptomatic with CO poisoning.
Cherokee County(GA) Firefighter