What role do carbon monoxide detectors play in building safety?

Carbon monoxide detectors are crucial for building safety because they specifically monitor the presence of carbon monoxide (CO), a colorless, odorless gas that can be highly toxic. High levels of carbon monoxide can result from the incomplete combustion of fossil fuels used in appliances such as gas stoves, heaters, and central heating systems. Since carbon monoxide is undetectable by human senses, these detectors provide an essential safety function by alerting occupants to its presence before it reaches dangerous levels, thereby preventing potential poisoning or death.

The other options do not accurately represent the function of carbon monoxide detectors: they do not prevent gas leaks, monitor humidity, or provide backup power, which helps clarify the distinctive safety role they play in protecting building occupants from the specific dangers associated with carbon monoxide exposure.