<unk>  connected to an electrical outlet<unk><unk>  alarm A<unk>  or CO<unk>  is a device that detects the presence of the<unk><unk>  (CO) gas to prevent<unk><unk>  poisoning. In the late 1990s Underwriters Laboratories changed the definition of a single station CO<unk>  with a sound device to<unk><unk>  (CO) alarm. This applies to all CO safety alarms that meet UL 2034 standard; however for passive indicators and system devices that meet UL 2075, UL refers to these as<unk> s. CO is a colorless, tasteless and odorless gas produced by incomplete combustion of<unk> -containing materials. It is often referred to as the "silent killer" because it is virtually undetectable by humans. In a study by Underwriters Laboratories, "Sixty percent of Americans could not identify any potential signs of a CO leak in the home". Elevated levels of CO can be dangerous to humans depending on the amount present and length of exposure. Smaller concentrations can be harmful over longer periods of time while increasing concentrations require diminishing exposure times to be harmful. CO<unk> s are designed to measure CO levels over time and sound an alarm before dangerous levels of CO accumulate in an environment, giving people adequate warning to safely ventilate the area or evacuate. Some system-connected<unk> s also alert a monitoring service that can dispatch emergency services if necessary. While CO<unk> s do not serve as smoke<unk> s and vice versa, combined smoke/CO<unk> s are also sold. In the home, some common sources of CO include open flames, space heaters, water heaters, blocked chimneys or running a car or grill inside a garage.
Carbon monoxide detector
Gaseous detection device
CO-oximeter
Respirometer
Respiratory pressure meter
Spirometer
Hyperoxia test
Multiple inert gas elimination technique