What's with the blue dots on the hotel ceiling?

This thing is called smoke detector, which can sense the concentration of smoke in the air. The process of fire is generally accompanied by three products: light, heat and smoke. At the beginning of the fire, because the temperature of combustion products is relatively low and in a smoldering state, a lot of smoke will be produced.

The function of carbon monoxide detector is to prevent the unknown fire from causing greater losses, and also for the safety of people's lives, so that people can find the fire in advance.