Fire alarm

The utility model discloses a fire alarm which comprises an outer shell, a smoke particle measurer is arranged in a cavity of the outer shell, an alarm is installed on the upper surface of the outer shell, a smoke channel is arranged at the front end of the outer shell and arranged in a through opening formed in the outer shell, and the smoke particle measurer is located at the end of the smoke channel. The end, away from the smoke particle measurer, of the smoke dust channel communicates with the outside of the outer shell. According to the utility model, the structure is novel, the smoke dust channel which is horizontally pulled and moved in the outer shell is adopted, the smoke dust channel can be quickly pulled out during cleaning, dust accumulated on the inner wall of the smoke dust channel can be removed through the cleaning ports on the upper and lower sides or by using a cleaning brush or by using clear water, and the outer shell does not need to be disassembled in the cleaning process; cleaning is ef