a compact air filtering device for filtering room air in the home or work environment constructed of a minimum number of unitary structural elements is disclosed , the device having a fan for drawing air through the device encased in detachably interlocked upper and lower enclosure members , one filter positioned on the upper fan enclosure member , and a housing detachably interlocked with the lower fan enclosure member enclosing the filter and the upper fan enclosure member . the device is adapted to receive additional filters identical in construction to the first filter by the addition of an intermediate housing member which increases the internal space within the device without any modification to any of the elements of the device .