Abstract: A direct plug-in air purifier, including a front shell, a rear shell, an air ionizer, a fan, and a front cover. The front shell includes a recessed portion configured to hold a mechanical air filter. The rear shell is attached to the front shell and includes an air outlet. The air ionizer and the fan are disposed in a space defined between the front shell and the rear shell. The front cover is releasably attached to the front shell and configured to allow air to pass therethrough. The fan is configured to draw air through the front cover, the mechanical filter, and an air guide formed in the recessed portion, and to expel air through the air outlet.