What device is intended to alert people to the presence of smoke in a building?

The device intended to alert people to the presence of smoke in a building is a smoke detector. Smoke detectors are specifically designed to sense smoke particles in the air and provide an early warning to occupants, which is crucial for ensuring safety and enabling timely evacuation in case of a fire.

Smoke detectors typically use either ionization or photoelectric technology to detect smoke and can respond to different types of fire conditions. This swift detection helps reduce the risk of injury or loss of life by alerting individuals before the fire grows larger and becomes more hazardous.

Devices such as heat detectors are designed to respond to temperature changes rather than smoke, making them less effective for early warning. Carbon monoxide detectors are focused on detecting the presence of carbon monoxide gas, which is a byproduct of combustion but not specifically related to smoke or fires. Fire alarm panels often serve to monitor multiple detectors and activate alarms, but they do not directly detect smoke themselves. Thus, the smoke detector is the correct answer for its specific function of alerting individuals to smoke presence.