A resolution of a local housing authority passed after the commencement of this section—
declaring an area to be a housing action area, excluding land from a housing action area or declaring that an area shall cease to be a housing action area, or
declaring an area to be a general improvement area, excluding land from a general improvement area or declaring that an area shall cease to be a general improvement area,
has effect, subject to subsection (2), from the day on which the resolution is passed.
A resolution declaring an area to be a general improvement area may be expressed to have effect from a future date, not later than four weeks after the passing of the resolution, on which the whole or part of that area will cease to be, or be included in, a housing action area.