An example of secondary pollutant is sulfurage
Displacement is shortest distance from starting point, 4km.
Use carbon dioxide and release oxygen gas
That is Loose Areolar connective tissue within the "Papillary" layer, for good capillary blood supply to the basement membrane of the epidermis.
The underlying "Reticular" dermal layer contains much more collagen in its matrix, which is a dense, irregular type of connective tissue.