A hand vacuum cleaner has an air treatment assembly comprising an air treatment chamber, the air treatment assembly comprising a central longitudinal axis that extends centrally through the air treatment assembly from a front end of the air treatment assembly to a rear end of the air treatment assembly, the air treatment assembly having a front openable door, a sidewall extending between the front end of the air treatment assembly and the rear end of the air treatment assembly and a discrete volume is provided between the front openable door and an interior dirt collection region of the air treatment assembly.