To begin, let's try to understand how we see the colours of the buildings and the trees. We "see" the colour of the light that is scattered off the surface of the building, leaves, etc, as shown.
|Scattering of light from surface (e.g. green wavelength em waves from the leaves) causes us to "see" the objects' colour|
|Effect of Rayleigh Scattering is small and hence don't produce the white haze|
With the dust particles, diameter in the region of microns (0.000001 m), suspended in the air, Mie scattering dominates. The scattering intensity by this process is larger than Rayleigh Scattering. The larger intensity of white light scattered from these particles (consisting of all visible wavelengths) is now more obvious to us.
|Mie Scattering off the dust particles produces the white haze seen the above photo|
|Red sky and sun around 6pm|
For more information on the different type of scattering, you may want to refer to this.